UNITED STATES


SECURITIES AND EXCHANGE
COMMISSION


Washington, D.C.
20549








FORM 10-K








[X] ANNUAL REPORT PURSUANT TO SECTION
13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934





For the
fiscal year ended December 31,
2007


or





[   ] TRANSITION REPORT
PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF
1934





For the
transition period from ________to _______





Commission
file number of issuing entity: 333-140436-11





MERRILL LYNCH MORTGAGE
INVESTORS TRUST, SERIES 2007-SL1


(Exact
name of issuing entity as specified in its charter)




Commission file number of depositor: 333-140436




Merrill Lynch Mortgage
Investors, Inc.


(Exact
name of registrant/depositor as specified in its charter)
  Merrill Lynch Mortgage
Lending, Inc.
 (Exact
name of sponsor as specified in its charter)


New
      York
            
            51-6590980
                51-6590981
                35-2298178
                35-2298177
                35-2298174(State
      or other jurisdiction of
              incorporation
      or organization)
            
            (I.R.S.
      Employer
              Identification
      No.)





c/o
LaSalle Bank National Association
 135 South
LaSalle Street, Chicago, Illinois 60603
 (Address of principal
executive offices)


312-904-7323
 (Registrant's
telephone number, including area code)


Securities
registered pursuant to Section 12(b) of the Act:




None




Securities
registered pursuant to Section 12(g) of the Act:




None




Indicate
by check mark if the registrant is a well-known seasoned issuer, as defined in
Rule 405 of the Securities Act.





oYes
            
            xNo





Indicate
by check mark if the registrant is not required to file pursuant to Section 13
or Section 15(d) of the Act.





oYes
            
            xNo





Indicate
by check mark whether the registrant (1) has filed all reports required to be
filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the
preceding 12 months (or for such shorter period that the registrant was required
to file such reports), and (2) has been subject to such filing requirements for
the past 90 days.





xYes
            
            oNo





Indicate
by check mark if disclosure of delinquent filers pursuant to Item 405 of
Regulation S-K (§229.405 of this
chapter) is not contained herein, and will not be contained, to the best of
registrant’s knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K.





x





Indicate
by check mark whether the registrant is a large accelerated filer, an
accelerated filer, a non- accelerated filer, or a small reporting
company.  See the definitions of “large accelerated filer,”
“accelerated filer” and “small reporting company” in Rule 12b-2 of the Exchange
Act.
 
 Large
      accelerated filer
              o
              Accelerated
      filer
              oNon-accelerated
      filer
              x
              (Do
      not check if a smaller reporting company)
              Smaller
      reporting company
              o




Indicate
by check mark whether the registrant is a shell company (as defined in Rule
12b-2 of the Act).   oYes  xNo




State the
aggregate market value of the voting and non-voting common equity held by
non-affiliates computed by reference to the price at which the common equity was
last sold, or the average bid and asked price of such common equity, as of the
last business day of the registrant’s most recently completed second fiscal
quarter.





Not
Applicable




DOCUMENTS INCORPORATED BY
REFERENCE




None




PART I
  Item 1.
Business.
 Omitted.
 
 Item 1A. Risk
Factors.
 Omitted.
 
 Item 1B. Unresolved Staff
Comments.
 None.
  Item 2.
Properties.
 Omitted.
 
 Item 3. Legal Proceedings.
 Omitted.
 
 Item 4. Submission of Matters to a
Vote of Security Holders.
 Omitted.
 
 
 PART II
 
 Item 5. Market for Registrant’s
Common Equity, Related Stockholder Matters and Issuer Purchases of Equity
Securities.
 Omitted.
 
 Item 6. Selected Financial
Data.
 Omitted.
 
 Item 7. Management’s Discussion and
Analysis of Financial Condition and Results of Operations.
 Omitted.
 
 Item 7A. Quantitative and Qualitative
Disclosures About Market Risk.
 Omitted.
 
 Item 8. Financial Statements and
Supplementary Data.
 Omitted.
 
 Item 9. Changes in and Disagreements
With Accountants on Accounting and Financial Disclosure.
 Omitted.
 
 Item 9A. Controls and
Procedures.
 Omitted.
  Item 9A(T). Controls and
Procedures.
 Omitted.
 Item 9B. Other
Information.
 None.
 
 PART III
 
 Item 10. Directors, Executive
Officers and Corporate Governance.
 Omitted.
 
 Item 11. Executive
Compensation.
 Omitted.
 
 Item 12. Security Ownership of
Certain Beneficial Owners and Management and Related Stockholder
Matters.
 Omitted.
 
 Item 13. Certain Relationships and
Related Transactions, and Director Independence.
 Omitted.
 
 Item 14. Principal Accounting Fees
and Services.
 Omitted.
  ADDITIONAL DISCLOSURE ITEMS UNDER
REGULATION AB
  Item
1112(b) of Regulation AB. Significant Obligors Financial
Information.
 No single
obligor represents 10% or more of the pool assets held by the issuing
entity.
  Item
1114(b)2 of Regulation AB, Significant Enhancement Provider Financial
Information.
 No entity
or group of affiliated entities provides any external credit enhancement or
other support for the certificates within this transaction as described under
Item 1114(a) of Regulation AB.
  Item
1115(b) of Regulation AB, Certain Derivatives Instruments (Financial
Information).
 The
significance percentages of the derivative transactions entered into on behalf
of the issuing entity are less than 10%.
 Item 1117 of Regulation AB. Legal
Proceedings.
 The
registrant knows of no material pending legal proceedings involving the Trust
and all parties related to such Trust, other than routine litigation incidental
to the duties of those respective parties.
 
 Item 1119 of Regulation AB.
Affiliations and Certain Relationships and Related
Transactions.
 The
information regarding this Item has been previously filed in a 424(b)(5) filing dated May
15, 2007.
  Item 1122 of Regulation AB.
Compliance with Applicable Servicing Criteria.
 See Item
15, exhibits (33) and (34)
  The
following information regarding LaSalle Bank National Association, as Securities
Administrator's material
instances of noncompliance and related remedial action was provided
by LaSalle Bank National Association, as Securities Administrator.
 LaSalle
Bank National Association’s (“LaSalle”) Report on Assessment of
Compliance with Servicing Criteria for 2007 (the “2007 Assessment”) attached to
this Report on Form 10-K describes in Appendix B the following material instance
of noncompliance related to investor reporting:
  “1122(d)(3)(i)(A)
and (B) – During the Reporting Period, certain monthly investor or remittance
reports were not prepared in accordance with the terms set forth in the
transaction agreements and certain investor reports did not provide the
information calculated in accordance with the terms specified in the transaction
agreements for which certain individual errors may or may not have been
material.”
  The
investor reporting errors identified on LaSalle’s 2007 Assessment as material
instances of noncompliance (the “Investor Reporting Errors”) included, for
example, revised delinquency, REO, foreclosure, repurchase, payoff or modified
loan counts, category indicators and/or balances.  The conclusion that
the Investor Reporting Errors amounted to a material instance of noncompliance
was based primarily on the aggregate number of errors as opposed to the
materiality of any one error.
  The
Investor Reporting Errors were generally caused by human error resulting
primarily from high volume monthly data processing demands that had to be
addressed within constricted time frames with less than a full complement of
operational staff.  Between the fourth quarter of the Reporting Period
and the date of the 2007 Assessment, LaSalle has employed additional operational
staff to accommodate the high volume of monthly investor reporting requirements
and minimize the risk of the Investor Reporting Errors
recurring.  Other necessary controls are in place to minimize the risk
of such errors.
  With
respect to the specific pool assets and asset-backed securities related to the
Investor Reporting Errors, the errors did not have, and are not reasonable
likely in the future to have, any material impact or effect on pool asset
performance, servicing of the pool assets and payments or expected payments on
the mortgage-backed securities.
  The
assessment of compliance of Litton Loan Servicing LP (“Litton”) disclosed the
following instances of noncompliance:
 Reconciliations for Asset-Backed
Securities Related Bank Account – 1122(d)(2)(vii)Investor bank account
reconciliations included certain reconciling items that were not resolved within
90 calendar days of their original identification.
  Loan Buyouts from Pool Assets –
1122(d)(4)(iii)Certain loan buyouts from pool assets were not made
within timeframes established in the transaction agreements.
  Loan Modifications – 1122(d)(4)(vi)Certain loans were modified during the Reporting Period that included a
modified maturity date that exceeded the latest maturity date established in the
transaction agreements.
  Litton
has implemented the following remediation procedures:
  Reconciliations for Asset-Backed
Securities Related Bank Account – 1122(d)(2)(vii)The controls over the
investor bank account reconciliation process are adequately designed and
operating effectively.  In the fourth quarter of 2007, Litton had
reduced the number of investor bank account reconciliations which included
reconciling items that were not resolved within 90 calendar days of their
original identification to less than 4%.
  Litton’s
key monitoring controls include an account reconciliation status report, and a
key performance indicator report which monitors bank account reconciliation
timeliness, and the percentage of accounts which have 90-day reconciling
items.  Senior servicing management review both of these monitoring
reports monthly.
  Loan Buyouts from Pool Assets –
1122(d)(4)(iii)Litton is in the process of incorporating automation that
will calculate the calendar month in which a loan can be bought out of
individual securities based on the requirements in the respective transaction
agreements. This automation will not allow a loan to be removed from a security
unless it is in the timeframe allowed in the respective transaction
agreements.  Litton expects to have this automation in place at or
around the end of the first quarter 2008.
 
 Loan Modifications – 1122(d)(4)(vi)In February 2008, Litton reviewed all of its transaction agreements and
updated its monitoring software with the latest maturity date a loan may be
modified for each security.  This software will systematically
prohibit loss mitigation personnel from modifying a loan with a maturity date
past the maturity date maintained in the system.
 Item 1123 of Regulation AB. Servicer
Compliance Statement.
 See Item
15, exhibit (35)
  Although
the referenced instances of noncompliance in the Litton report on assessment of
compliance with the servicing criteria were material to the activities of Litton
on a platform level, the instances of noncompliance related to reconciliations
and loan modifications did not relate specifically to the performance of Litton
in its capacity as servicer under the pooling and servicing agreement related to
the securities issued by the Issuing Entity. Accordingly, the servicer
compliance statement of Litton was appropriately modified.
 PART IV
 
 Item 15. Exhibits, Financial
Statement Schedules.
 
 (a) The
following is a list of documents filed as part of this Annual Report on Form
10-K:
 (1) Not
Applicable
 (2) Not
Applicable
 (3)
 Exhibit
      Number
                      Description4.1
                      Trust
      Agreement (filed as an exhibit to Form 8-K on
  2007-05-29)4.2
                      Indenture
      (filed as an exhibit to Form 8-K on 2007-05-29)10.1
                      Mortgage
      Loan Sale and Assignment Agreement (filed as an exhibit to Form 8-K on
      2007-05-29)10.2
                      Mortgage
      Loan Purchase Agreement (filed as an exhibit to Form 8-K on
      2007-05-29)10.3
                      Administration
      Agreement (filed as an exhibit to Form 8-K on
      2007-05-29)31
                      Sarbanes-Oxley
      Certification33(a)
                      Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, LaSalle Bank National Association, as Master
      Servicer33(b)
                      Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, Litton Loan Servicing LP, as Servicer33(c)
                      Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, Wilshire Credit Corporation, as Servicer33(d)
                      Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, Countrywide Home Loans Servicing LP, as
    Servicer33(e)
                      Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, LaSalle Bank National Association, as Securities
      Administrator33(f)
                      Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, LandAmerica Tax and Flood Services, Inc., as Servicing
      Function Participant33(g)
                      Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, ZC Sterling Insurance Agency, Inc., as Servicing Function
      Participant34(a)
                      Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, LaSalle Bank National Association, as Master
      Servicer34(b)
                      Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, Litton Loan Servicing LP, as
    Servicer34(c)
                      Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, Wilshire Credit Corporation, as
      Servicer34(d)
                      Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, Countrywide Home Loans Servicing LP, as
      Servicer34(e)
                      Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, LaSalle Bank National Association, as Securities
      Administrator34(f)
                      Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, LandAmerica Tax and Flood Services, Inc., as
      Servicing Function Participant34(g)
                      Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, ZC Sterling Insurance Agency, Inc., as Servicing
      Function Participant35(a)
                      Servicer
      compliance statement, LaSalle Bank National Association, as Master
      Servicer35(b)
                      Servicer
      compliance statement, Litton Loan Servicing LP, as
  Servicer35(c)
                      Servicer
      compliance statement, Wilshire Credit Corporation, as
    Servicer35(d)
                      Servicer
      compliance statement, Countrywide Home Loans Servicing LP, as
      Servicer35(e)
                      Servicer
      compliance statement, LaSalle Bank National Association, as Securities
      Administrator





(b) The
exhibits required to be filed by Registrant pursuant to Item 601 of Regulation
S-K:
 
 (31) Rule
13a-14(d)/15d-14(d) Certifications.
 
 (33)
Reports on assessment of compliance with servicing criteria for asset-backed
securities:
 LaSalle
      Bank National Association, as Master ServicerLitton
      Loan Servicing LP, as ServicerWilshire
      Credit Corporation, as ServicerCountrywide
      Home Loans Servicing LP, as ServicerLaSalle
      Bank National Association, as Securities AdministratorLandAmerica
      Tax and Flood Services, as Servicing Function
  ParticipantZC
      Sterling Insurance Agency, Inc. as Servicing Function
      Participant
 
 (34)
Attestation reports on assessment of compliance with servicing criteria for
asset-backed securities:
 LaSalle
      Bank National Association, as Master ServicerLitton
      Loan Servicing LP, as ServicerWilshire
      Credit Corporation, as ServicerCountrywide
      Home Loans Servicing LP, as ServicerLaSalle
      Bank National Association, as Securities AdministratorLandAmerica
      Tax and Flood Services, as Servicing Function
  ParticipantZC
      Sterling Insurance Agency, Inc. as Servicing Function
      Participant
  (35)
Servicer Compliance Statements:
 LaSalle
      Bank National Association, as Master ServicerLitton
      Loan Servicing LP, as ServicerWilshire
      Credit Corporation, as ServicerCountrywide
      Home Loans Servicing LP, as ServicerLaSalle
      Bank National Association, as Securities
  Administrator




(c) Not
Applicable.











SIGNATURES




LaSalle
      Bank National Association, as Master ServicerMarch
      28, 2008
              /s/ Tammy
      SpriggsBy: Tammy
      SpriggsTitle: First
      Vice PresidentSenior
      Officer in Charge of Securitization of theMaster
      Servicer










Exhibit
      Number
            Description4.1
            Trust
      Agreement (filed as an exhibit to Form 8-K on
  2007-05-29)4.2
            Indenture
      (filed as an exhibit to Form 8-K on 2007-05-29)10.1
            Mortgage
      Loan Sale and Assignment Agreement (filed as an exhibit to Form 8-K on
      2007-05-29)10.2
            Mortgage
      Loan Purchase Agreement (filed as an exhibit to Form 8-K on
      2007-05-29)10.3
            Administration
      Agreement (filed as an exhibit to Form 8-K on
      2007-05-29)31
            Sarbanes-Oxley
      Certification33(a)
            Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, LaSalle Bank National Association, as Master
      Servicer33(b)
            Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, Litton Loan Servicing LP, as Servicer33(c)
            Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, Wilshire Credit Corporation, as Servicer33(d)
            Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, Countrywide Home Loans Servicing LP, as
    Servicer33(e)
            Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, LaSalle Bank National Association, as Securities
      Administrator33(f)
            Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, LandAmerica Tax and Flood Services, Inc., as Servicing
      Function Participant33(g)
            Report
      on assessment of compliance with servicing criteria for asset-backed
      securities, ZC Sterling Insurance Agency, Inc., as Servicing Function
      Participant34(a)
            Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, LaSalle Bank National Association, as Master
      Servicer34(b)
            Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, Litton Loan Servicing LP, as
    Servicer34(c)
            Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, Wilshire Credit Corporation, as
      Servicer34(d)
            Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, Countrywide Home Loans Servicing LP, as
      Servicer34(e)
            Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, LaSalle Bank National Association, as Securities
      Administrator34(f)
            Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, LandAmerica Tax and Flood Services, Inc., as
      Servicing Function Participant34(g)
            Attestation
      report on assessment of compliance with servicing criteria for
      asset-backed securities, ZC Sterling Insurance Agency, Inc., as Servicing
      Function Participant35(a)
            Servicer
      compliance statement, LaSalle Bank National Association, as Master
      Servicer35(b)
            Servicer
      compliance statement, Litton Loan Servicing LP, as
  Servicer35(c)
            Servicer
      compliance statement, Wilshire Credit Corporation, as
    Servicer35(d)
            Servicer
      compliance statement, Countrywide Home Loans Servicing LP, as
      Servicer35(e)
            Servicer
      compliance statement, LaSalle Bank National Association, as Securities
      Administrator