**CERTIFICATION      OF PRINCIPAL EXECUTIVE OFFICER**

| 1.   | I              have reviewed this annual report on Form 10-K of United Development              Funding III, L.P.; |
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| 2.   | Based              on my knowledge, this report does not contain any untrue statement              of a              material fact or omit to state a material fact necessary to make the              statements made, in light of the circumstances under which such statements              were made, not misleading with respect to the period covered by this              report; |
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| 3.   | Based              on my knowledge, the financial statements, and other financial information              included in this report, fairly present in all material respects the              financial condition, results of operations and cash flows of the              registrant as of, and for, the periods presented in this              report; |
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| 4.   | The              registrant’s other certifying officer and I are responsible for              establishing and maintaining disclosure controls and procedures (as              defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant              and have: |
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|   | (a) | Designed                such disclosure controls and procedures, or caused such disclosure                controls and procedures to be designed under our supervision, to                ensure                that material information relating to the registrant, including its                consolidated subsidiaries, is made known to us by others within those                entities, particularly during the period in which this report is                being                prepared; |
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|   | (b) | Intentionally                omitted; |
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|   | (c) | Evaluated                the effectiveness of the registrant’s disclosure controls and procedures                and presented in this report our conclusions about the effectiveness                of                the disclosure controls and procedures as of the end of the period                covered                by this report based on such evaluation;                and |
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|   | (d) | Disclosed                in this report any change in the registrant’s internal control over                financial reporting that occurred during the registrant’s most recent                fiscal quarter (the registrant’s fourth fiscal quarter in the case of our                annual report) that has materially affected, or is reasonably likely                to                materially affect, the registrant’s internal control over financial                reporting; and |
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| 5.   | The              registrant’s other certifying officer and I have disclosed, based on our              most recent evaluation of internal control over financial reporting,              to              the registrant’s auditors and the audit committee of the registrant’s              board of directors (or persons performing the equivalent              functions): |
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|   | (a) | All                significant deficiencies and material weaknesses in the design or                operation of internal control over financial reporting which are                reasonably likely to adversely affect the registrant’s ability to record,                process, summarize and report financial information;                and |
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|   | (b) | Any                fraud, whether or not material, that involves management or other                employees who have a significant role in the registrant’s internal control                over financial reporting. |
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| Dated              this 2nd day of April, 2007. | By:                                                                                                                                                                                                                                                                         | /s/ Hollis              M. Greenlaw |
|                                            | Hollis M. Greenlaw                                                                                                                                                                                                                                                                    |
|                                            | Chief              Executive Officer of UMTH Land Development, L.P., sole general partner              of              the Registrant, and President and Chief Executive Officer of UMT Services,              Inc., sole general partner of UMTH Land Development,              L.P. |