<PAGE>  1
                                                             Exhibit 10(b)

                                                  April 12, 2004

Tom Bolger
c/o Marshall & Ilsley Corporation
770 North Water Street
Milwaukee, Wisconsin  53202


Dear Tom:

     This Letter Agreement ("Letter Agreement") is intended to reflect our
agreement concerning your early retirement from Marshall & Ilsley Corporation
("M&I") and all related matters.

          1.   Status of Employment Through June 30, 2004.  From the date
     of this letter through June 30, 2004 (the "Full-Time Employment
     Period"), you will remain a full-time employee of M&I.  You will
     continue to report to Dennis Kuester.  During the Full-Time Employment
     Period, your compensation and benefits will remain the same as they were
     immediately prior to the date of this letter.  On July 1, 2004, the
     title to your current company vehicle will be transferred to you at no
     cost.  The value of the company vehicle will be reported for income tax
     purposes as compensation to you, with value determination and taxable
     income allocation pursuant to the Marshall & Ilsley Corporation
     Automobile Policy - 2004.  M&I will pay you an incentive for the six-
     month period beginning January 1 and ending June 30, 2004 in the amount
     of $240,000 no later than July 31, 2004 if you comply with the
     following:  (a) you assist in a positive transition of your
     responsibilities and (b) you execute, and do not revoke during the
     applicable rescission period, the Complete and Permanent Release
     provided to you once the Full-Time Employment Period ends.

          2.   Status of Employment from July 1, 2004 through
     December 31, 2005.  From July 1, 2004 through December 31, 2005
     (the "Part-Time Employment Period"), you will be a part-time
     employee of M&I, working less than 17.5 hours per week, and you
     will continue to report to Dennis Kuester; however, none of the
     payments or benefits promised to you herein are or will be
     contingent upon your performance of duties other than ones that
     the parties (including you) shall mutually agree in writing after
     the end of the Full-Time Employment Period (instead the payments
     and benefits in this Letter Agreement will be guaranteed as set
     forth in this document).  During the Part-Time Employment Period,
     you agree not to take any action, perform any duties, or incur any
     expenses on M&I's behalf without Dennis Kuester's written
     direction.  Throughout the Part-Time Employment Period, you will
     receive monthly payments of $72,000, totaling $1,296,000, in
     accordance with M&I's regular payroll practices.  Because of the
     reduction in your hours of employment, you will be eligible to
     participate in M&I's health and dental plans to the extent that
     you elect continuation coverage in accordance with the
     Consolidated Omnibus Budget Reconciliation Act of 1985, as amended
     ("COBRA").  M&I will subsidize your health and dental coverage
     (including payment of your COBRA premiums) to the same extent as
     for full-time active employees through and until June 30, 2006.
     This continued subsidy will last through and until June 30, 2006,
     notwithstanding the fact that COBRA will run out December 31,
     2005; such that you will continue to participate in M&I's health
     and dental plans through June 30, 2006 as if you remained an
     active, full-time employee, and M&I will continue to subsidize
     your participation to the same extent as for full-time active
     employees.  Starting on July 1, 2006, you will be eligible to
     participate in the M&I Retiree Medical Program, and any other
     retirement plans or programs which similarly situated M&I retirees

<PAGE>  2
     (excluding retirees of companies acquired by M&I who may have been
     provided benefits according to the terms of an acquisition agreement)
     enjoy, in accordance with their terms as in effect from time to time
     pursuant to similar treatment of other similarly-situated retirees, if
     you have remained a participant in the M&I health plans through June 30,
     2006.  Because of your part-time employment starting on July 1, 2004,
     you will not be eligible to participate in any of M&I's other benefit
     plans (other than ones specified in this Letter Agreement) including
     M&I's long-term disability plans.  This does not, however, limit in any
     way, your right to purchase the conversion coverage provided by the
     United Wisconsin Life Insurance Program.  Any vested benefits you have
     in M&I's qualified or nonqualified benefit plans as of December 31, 2005
     will thereafter be governed by the terms of those plans, except as such
     rights are set forth otherwise in this Agreement, in which case the
     terms of this Agreement shall prevail.  As of December 31, 2005, you
     will be deemed to have utilized all vacation to which you may be
     eligible and, therefore, will not be entitled to any payment for earned,
     but unused, vacation.  In addition, you agree not to apply for
     unemployment compensation benefits from M&I respecting the end of your
     employment with it.

          3.   Salary and Incentive Continuation Payments.  For the
     period beginning January 1, 2006 and ending on June 30, 2006, you
     shall receive monthly payments of $72,000, totaling $432,000, if
     you execute, and do not revoke during the applicable rescission
     period, the second Complete and Permanent Release provided to you
     once the Part-Time Employment Period ends.

          4.   Treatment of Stock Options.  Any M&I stock options
     which by their terms will vest on or before December 31, 2005 will
     do so in accordance with their terms and in accordance with your
     status as an employee until December 31, 2005, and the fact that
     your employment status changes from Full-Time to Part-Time on July
     1, 2004 shall have no effect on your rights to have these options
     vest.  Any M&I stock options which do not vest on or before
     December 31, 2005 will lapse as of January 1, 2006.  The normal
     terms of the relevant M&I Stock Option Plans provide that the
     options remain exercisable for ninety days after your employment
     terminates.  However, notwithstanding the terms of those Stock
     Option Plans, with regard to your vested options (as of December
     31, 2005), you will be eligible for retiree treatment and
     therefore your vested options will remain exercisable for the
     shorter of (a) the remainder of their terms as if your employment
     continued indefinitely or (b) one year after your death, but only
     if, and to the extent, you choose to meet the following two
     conditions.  First, you execute, and do not revoke during the
     applicable rescission period, the second Complete and Permanent
     Release provided to you once the Part-Time Employment Period ends.
     Second, you comply with the confidentiality and non-competition
     provisions set forth in paragraphs 13 and 14 of this Letter
     Agreement, not only for the term set forth in those paragraphs,
     but for such longer period as you want your options to remain
     exercisable.  Should you violate any provision of paragraph 13 or
     14 during the term set forth therein, or the extended term of your
     choosing, you agree that your outstanding M&I stock options
     (including those transferred to family members) shall, without any
     action by M&I (other than providing notice), remain exercisable
     only for the shorter of the remainder of their respective terms
     or the ninety (90) day period running from the date of your
     breach; provided that the ninety (90) day period shall not start
     running until the date on which M&I provides you with written
     notice of breach; and further provided that this language shall
     have no impact on your LTIP entitlements delineated in Paragraph
     6 of this Letter Agreement.  The provisions of this Paragraph 4
     shall not apply to the restricted units discussed below in
     Paragraph 5.

          5.   Vesting of Restricted Stock. All restricted units that
     have not vested by December 31, 2005 will automatically vest on
     December 31, 2005 or January 1, 2006, at your choice (and if you
     choose January 1, 2006, then the language and terms contained in
     this Letter Agreement referencing expiration of your unvested
     stock as of December 31, 2005 shall instead mean as of January 1,
     2006, such that your unvested restricted units shall not be deemed
     to have expired or been forfeited on or as of December 31, 2005)

<PAGE>  3
          6.   Participation in the Long-Term Incentive Plan.  You
     will continue to participate in the awards made to you under M&I's
     1994 Long-Term Incentive Plan (the "LTIP") which relate to the
     periods ended December 31, 2004 and 2005 in the amount of 8,000
     units in each year.  You will be treated as an age 65 retiree from
     M&I as regards the 10,000 units which were awarded to you under
     the LTIP in December 2003 for the performance period ended
     December 31, 2006.  Any incentive owing to you in connection with
     such awards will be paid to you at such time and upon such terms
     as payments are made to other participants.  Your continued
     participation with respect to your outstanding LTIP units shall
     not be impacted in any manner if you choose to breach the terms
     of Paragraphs 13 or 14 of this Letter Agreement after December 31,
     2005.

          7.   Participation in the Deferred Compensation Plan.  Your
     right to make additional deferrals into M&I's Amended and Restated
     Executive Deferred Compensation Plan (the "Deferred Compensation
     Plan") will end on December 31, 2005; however, notwithstanding the
     terms of the Deferred Compensation Plan, you will be given an
     opportunity after you execute this Agreement to
     redeclare/reallocate under the Deferred Compensation Plan for the
     last six months of calendar year 2004.  The balance in your
     Account, as defined therein, will be distributed to you in
     accordance with your form of Payment Election in accordance with
     that Plan's terms.  To the extent that the deductibility of any
     payments made to you under this Letter Agreement would be limited
     by Section 162(m) of the Internal Revenue Code, such payments will
     automatically be deferred into your account in the Deferred
     Compensation Plan, whenever such amounts are otherwise due and
     owing to you.

          8.   Retirement Contributions.  M&I will make retirement
     contributions totaling $183,000 related to the services you
     perform in 2004 and 2005.  The contributions for each year will
     total $91,500, and will first be contributed to the qualified
     retirement plans to the maximum extent provided by law, including
     as an employer match under M&I's 401(k) plan, with the remainder
     contributed to your account in the Deferred Compensation Plan.

          9.   Club Dues and Tax and Financial Planning Fees.  M&I
     will pay you a lump sum of $30,000, to cover your membership dues
     and annual (but not extraordinary) capital assessments at your
     clubs for the 2004 and 2005 calendar years and your income tax
     preparation for your 2004 and 2005 federal and state income tax
     returns and associated financial planning in accordance with M&I's
     policies for executive officers, as well as other financial
     planning costs.  This payment will be made consistently with the
     tax treatment and reimbursement methods as are used with the
     Company's senior most executives, and to the extent that any of
     the Company's senior most executives may be given tax favorable
     treatment or tax gross-up, then you would be treated and given the
     same.  The value of these benefits, to the extent required by law,
     will be reported for income tax purposes.  M&I's obligations under
     this Paragraph 9 regarding financial counseling, tax preparation,
     and club fees, dues and costs will be capped at a total of
     $30,000, but you will receive a total of $30,000 in benefit and/or
     payment pursuant to this Paragraph 9, regardless of your actual
     expenses and costs.  In addition to this $30,000 payment, M&I will
     reimburse you for your legal costs in having this Agreement
     reviewed and negotiated on your behalf, up to a cap of $10,000.

          10.  Impact of Life Insurance and Disability Payments.  If
     you should suffer a disability between the date of this Letter
     Agreement and June 30, 2004 such that you would qualify for short-
     term or long-term disability payments under the M&I Short-Term
     Disability Leave Policy or the Marshall and Ilsley Corporation
     Long-Term Disability Income Plan, the present value of any
     projected payments will reduce any amounts owing to you under this
     Letter Agreement.  The present value will be computed assuming
     disability payments will continue for the maximum amount of time
     allowed under each plan.  Should your right to disability payments
     end prior to the receipt of the maximum payments, the present
     value will be recomputed based on the actual number of disability
     payments you received, and any excess reduction will be paid to

<PAGE>  4
     you within thirty days of the date you no longer receive disability
     payments.  If you were to die during the period between the date of this
     Letter Agreement and June 30, 2004, any life insurance proceeds from an
     M&I plan that are paid to your beneficiaries will reduce the amounts
     paid to your beneficiaries under this Letter Agreement on a dollar-for-
     dollar basis.  Notwithstanding the foregoing, however, M&I understands
     that you have been and through June 30, 2004 will be continuing to pay
     the cost of group life insurance premiums to obtain additional death
     benefit beyond what the Company's premium payments cover, and therefore,
     in the event of your death on or prior to June 30, 2004, then the amount
     of life insurance paid out as a result of your paid premiums will not
     be offset in anyway against the amounts paid to your beneficiaries under
     this Letter Agreement.

          11.  Change of Control Agreement.  Your Change of Control
     Agreement with M&I dated August 12, 1999 shall terminate on the
     date you execute this Letter Agreement.

          12.  Other Agreements.  In exchange for the benefits
     provided to you in this Letter Agreement, you agree as follows:

               (a)  You acknowledge that you and M&I have agreed on
          the form of press release announcing your early retirement
          and the related communication plan.

               (b)  You agree that your positions as President of
          M&I Marshall & Ilsley Bank and Executive Vice President of
          M&I, as well as any other officer and director positions
          you then hold with M&I or any other subsidiary or affiliate
          of M&I, will end as of 5:00 p.m. (C.D.T.) on June 30, 2004,
          and that no additional action is required by you in
          connection with the end of your tenure in such positions.

               (c)  You hereby resign as a director of M&I Marshall
          & Ilsley Bank and Metavante Corporation effective as of
          5:00 p.m. (C.D.T.) on April 12, 2004.

               (d)  You agree that any transactions by you in M&I
          stock prior to the date on which M&I reports its calendar
          year 2004 earnings are subject to the "Pre-Clearance"
          provision of the M&I Securities Trading Policy, but that
          after that date, you shall be subject only to applicable
          law.

          13.  Confidentiality.  In exchange for the benefits
     provided to you above, you agree to be bound by the provisions of
     Paragraphs 13 and 14 of this Letter Agreement.  The term
     "Company," as used in Paragraphs 13 and 14 hereof, means M&I and
     any Affiliate.  "Affiliate" means any corporation, partnership,
     limited liability company or other business entity which, directly
     or indirectly through one or more intermediaries, is controlled
     by M&I.  The term "control" means the power, directly or
     indirectly, to vote 50% or more of the securities which have
     ordinary voting power in the election of directors (or individuals
     filling any analogous positions).

               (a)  Confidential Information.  During the Full-Time
          Employment Period, the Part-Time Employment Period, and
          until June 30, 2006, you shall not make any Unauthorized
          Disclosure.  For purposes of this Agreement, "Unauthorized
          Disclosure" shall mean your use or direct or indirect
          disclosure, without the consent of the Board of Directors
          of M&I, to any person, other than use or disclosure that
          may be legally required (provided the provisions of
          Paragraph 13(c) hereof are complied with), of any
          confidential information obtained by you while in the
          employ of M&I, including, but not limited to, confidential
          information with respect to any of the Company's customers,
          business plans, financial results and pricing, methods of

<PAGE>  5
          operation, services and products (the "Confidential Information");
          provided, however, that Confidential Information shall not include
          any information which was or becomes generally available to the
          public other than as a result of a wrongful disclosure by you, or
          which M&I previously publicly discloses.  Nothing herein shall
          limit your confidentiality obligation as regards any information
          which is a trade secret as currently defined in the Wisconsin
          Uniform Trade Secrets Act, or any successor thereto, which you
          acknowledge may extend beyond June 30, 2006.

               (b)  Return of Property.  All memoranda, notes,
          records, other documents, customer lists, software,
          computer files, and equipment, and all copies thereof,
          relating to the operations or business of the Company, some
          of which may be prepared by you, and all objects associated
          therewith in any way obtained by you in connection with the
          performance of your duties for M&I, shall be the exclusive
          property of M&I.  You shall not copy or duplicate any of
          the aforementioned, nor use any information concerning them
          other than in accordance with the performance of your
          duties for M&I.  You will, no later than June 30, 2004, (i)
          deliver the original and all copies of all of the
          aforementioned that may be in your possession to M&I and
          (ii) delete any such information on your home or laptop
          computer.

               (c)  Legally-Required Disclosure.  If you are
          requested or become legally required or compelled (by oral
          questions, interrogatories, requests for information or
          documents, subpoena, civil or criminal investigative
          demand, or similar process) or are required by a
          governmental body to make any disclosure that is prohibited
          or otherwise constrained by this Letter Agreement, you will
          provide M&I with prompt written notice of such request so
          that it may seek an appropriate protective order or other
          appropriate remedy.  Subject to the foregoing, you may
          furnish that portion (and only that portion) of the
          Confidential Information that you are legally compelled or
          are otherwise required to disclose.

          14.  Non-Competition and Nonsolicitation.  In exchange for
     the benefits provided to you above, you agree to be bound by the
     provisions of Paragraph 14 of this Letter Agreement, all of which
     are severable.

               (a)  Nonsolicitation of Customers. During the Full-
          Time Employment Period, the Part-Time Employment Period,
          and until June 30, 2006, you agree not to solicit, entice
          or encourage any Customer of the Company so as to cause or
          attempt to cause such Customer not to do business with the
          Company, to diminish its business with the Company, or to
          purchase a products or services sold by the Company from
          any source other than the Company.  For purposes of this
          paragraph, "Customer" shall mean any person or business (i)
          which had a borrowing or depository relationship with the
          Company during any part of the one (1) year period prior to
          June 30, 2004 or (ii) which purchased products or services
          from the Company during the one (1) year period preceding
          the June 30, 2004; and (iii) with whom you had Direct
          Contact on behalf of the Company during such one (1) year
          period.  For purposes of this Paragraph 14(a) of this
          Letter Agreement, the term "Direct Contact" means "focused
          intentional contact by you to either maintain or enhance
          M&I's business relationship with customer, whether contact
          was in person, by phone, or in writing."  Thus, the
          prohibitions contained in this Paragraph 14(a) of this
          Letter Agreement do not cover Customers with whom you did
          not have Direct Contact during the one (1) year period
          preceding June 30, 2004.

<PAGE>  6
               (b)  Non-Solicitation of Employees.  During the
          Full-Time Employment Period, the Part-Time Employment
          Period, and until June 30, 2006, you will not induce or
          attempt to induce any individual who was employed by M&I on
          June 30, 2004 (a "Covered Employee") to terminate his or
          her employment with, or reduce the hours he or she works
          for, M&I.

               (c)  General Non-Competition Provisions.  During the
          Full-Time Employment Period, the Part-Time Employment
          Period, and until June 30, 2006, you agree not to directly
          or indirectly perform services substantially similar to the
          type performed by you for M&I for any Competitor of the
          Company where the services you provide benefit any of the
          Competitor's business activities (as long as such business
          activities are ones that M&I engages in) in (i) the State
          of Wisconsin, , (iii) within Phoenix, Arizona or a 75-mile
          radius of Phoenix, Arizona, (iv) within Tuscon, Arizona or
          a 40-mile radius of Tucson, Arizona, or (v) within
          Minneapolis, Minnesota or a 40-mile radius of Minneapolis,
          Minnesota.  A "Competitor" means an entity in the financial
          services business which is engaged in deposit taking,
          lending, or trust products or services, in the same manner
          as M&I.  Notwithstanding the foregoing, after December 31,
          2005, you may violate the terms of this Paragraph 14(c) of
          this Letter Agreement in the states of Arizona and
          Minnesota, and if you do, then the Company shall,
          commencing on the date of your violation, be relieved of
          its obligations to continue paying you prospectively any
          remaining unpaid Salary and Incentive Continuation Payments
          referenced in Paragraph 3 of this Letter Agreement and your
          outstanding M&I stock options (including those transferred
          to family members) shall, without any action by M&I (other
          than providing you with written notice of the acceleration
          of your exercise period), remain exercisable only for the
          shorter of the remainder of their respective terms or the
          ninety (90) day period running from the date of your
          violation; however, your violation of the terms of
          Paragraph 14(c) with respect to the states of Arizona and
          Minnesota after December 31, 2005 shall have no other
          detrimental effect to you, and shall not otherwise reduce
          your entitlements under this Letter Agreement.

               (d)  Acknowledgements/Consequences of Breach.  You
          acknowledge that irreparable and incalculable injury will
          result to M&I, its business or properties, in the event of
          a breach by you of any of the restrictions set forth in
          Paragraphs 13 and 14 of this Letter Agreement.  You
          therefore agree that, in the event of any such actual,
          impending or threatened breach, M&I will be entitled, in
          addition to any other remedies, to temporary and permanent
          injunctive relief (without the necessity of posting a bond
          or other security) restraining the violation or further
          violation of such restrictions by you.  In addition, M&I
          shall be entitled to recover from you the monetary value of
          all consideration paid to you under this Letter Agreement,
          as well as to suspend all future payments and benefits
          which might otherwise be due you by them.  The election of
          any one or more remedies by M&I shall not constitute a
          waiver of the right to pursue other available remedies.
          You further acknowledge that: (a) you will be able to earn
          a livelihood without violating the foregoing restrictions,
          (b) the covenants and restrictions set forth in Paragraphs
          13 and 14 are necessary to protect the legitimate business
          interests of the Company and (c) your compliance with the
          terms of Paragraphs 13 and 14 are material terms.

          15.  Miscellaneous.  Upon your execution of this Letter
     Agreement, the following will apply:

               (a)  Severability.  The sections, subsections,
          paragraphs and subparagraphs of this Letter Agreement are
          severable, and in the event any such section, subsection,
          paragraph or subparagraph may be held to be invalid by such
          court, this Letter Agreement shall be interpreted as if any
          such invalid section, subsection, paragraph or subparagraph
          were not contained in this Letter Agreement.

<PAGE>  7
               (b)  Entire Agreement; Amendment.  This Letter
          Agreement and the Complete and Permanent Releases (jointly,
          the "Agreements") constitute the complete understanding
          between you and M&I, concerning all matters affecting your
          employment with M&I and the termination thereof.  If you
          execute this Letter Agreement, the Agreements supersede, as
          of the date of your consent to each of them, all prior
          agreements, understandings, personnel documents, handbooks,
          policies and any prior customs or practices concerning such
          matters, including the Change of Control Agreement between
          you and M&I dated August 12, 1999.  This Letter Agreement
          may not be amended without the written consent of M&I and
          you.  However, any side letters, if any, shall become a
          part of this Letter Agreement by a side letter making
          express reference to this Letter Agreement.

               (c)  Governing Law.  The Agreements and their
          interpretation shall be governed and construed in
          accordance with the laws of Wisconsin, without regard to
          its principles of conflicts of laws, and shall be binding
          upon the parties hereto and their respective successors and
          assigns.

               (d)  Other Treatment.  The amounts to be paid to you
          are in lieu of any severance or other termination benefits
          you would otherwise be entitled to under any other plan or
          arrangement of M&I, and such amounts will not count as
          compensation for purposes of any qualified or nonqualified
          retirement or welfare benefit plans except as otherwise
          expressly provided herein.  All dollar amounts set forth
          herein are stated prior to deduction for any applicable
          income and employment tax withholding, or such other
          deduction as may be required by law.

               (e)  Death or Disability.  In the event of your
          death, M&I shall continue to make the payments and provide
          the benefits specified herein to your spouse or other
          designated beneficiary (or in the event such beneficiary
          predeceases you, to your estate), adjusted as provided in
          paragraph 10 of this Letter Agreement if you were to die
          prior to July 1, 2004.  In the event of your disability,
          M&I shall continue to make the payments and provide the
          benefits specified herein, adjusted as provided in
          paragraph 10 of this Letter Agreement if you were to become
          disabled prior to July 1, 2004, directly to you, or, if
          another person or entity has been appointed to handle your
          financial affairs because you are unable to do so, to that
          person or entity.

          16.  Consents, Approvals and Authorizations.  M&I warrants
     and represents to you that all consents, approvals and
     authorizations required for M&I to execute, deliver and perform
     this Letter Agreement have been obtained and are in full force and
     effect as of the date hereof, and the Agreements are valid,
     binding and enforceable obligations of M&I in accordance with
     their terms.

          17.  No Mitigation Obligation.  To the extent that you
     choose to pursue other opportunities prior to July 1, 2006, such
     pursuits shall have no effect on your entitlement to all payments,
     benefits and promises owed to you by M&I under this Agreement
     (assuming your compliance with this Agreement), as such payments,
     benefits and promises are guaranteed.  Moreover, you are under no
     obligation to mitigate in relation to the changes in your
     employment status with M&I.  The fact that you are under no
     obligation to mitigate shall have no effect on your obligations
     to M&I regarding confidentiality, non-competition and
     nonsolicitation contained in Paragraphs 13 and 14 of this
     Agreement.

          18.  Counterparts.  This Agreement may be executed in
     counterparts, all of which taken together shall constitute one
     Agreement.

<PAGE>  8
     You may accept this Letter Agreement by signing it in the space provided
below and returning it to Paul Renard at Marshall & Ilsley Corporation, 770
North Water Street, Milwaukee, Wisconsin, 53202.

                              Very truly yours,

                              MARSHALL & ILSLEY CORPORATION


                              By:  /s/ David J. Mauer
                                   _________________________________

                                   David J. Mauer
                                   Vice President Human Resources


     I agree with and accept the above-mentioned terms contained in this
Letter Agreement and agree to be bound by them.

Dated this 12th day of April, 2004.

/s/ Thomas M. Boldger
___________________________________