SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to Rule 13d-1(b), (c) and (d) and Amendments Thereto Filed Pursuant to Rule 13d-2. Under the Securities Exchange Act of 1934 (Amendment No. ____)* SI International, Inc. -------------------------------------------------------------------------------- (Name of Issuer) Common Stock -------------------------------------------------------------------------------- (Title of Class of Securities) 78427V102 -------------------------------------------------------------------------------- (CUSIP Number) July 31, 2007 -------------------------------------------------------------------------------- (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: [X] Rule 13d-1(b) [_] Rule 13d-1(c) [_] Rule 13d-1(d) * The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). Page 1 of 15 CUSIP No. 78427V102 13G ------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON / I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Artisan Partners Limited Partnership ------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) [_] (see Instructions) (b) [_] Not Applicable ------------------------------------------------------------------------------- 3 SEC USE ONLY ------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ------------------------------------------------------------------------------- 5 SOLE VOTING POWER None ----------------------------------------------------------------- NUMBER OF 6 SHARED VOTING POWER SHARES BENEFICIALLY 1,533,300 OWNED BY ----------------------------------------------------------------- EACH 7 SOLE DISPOSITIVE POWER REPORTING PERSON None WITH ----------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 1,710,700 ------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,710,700 ------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable ------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 13.1% ------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) IA ------------------------------------------------------------------------------- Page 2 of 15 CUSIP No. 78427V102 13G ------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON / I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Artisan Investment Corporation ------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) [_] (see Instructions) (b) [_] Not Applicable ------------------------------------------------------------------------------- 3 SEC USE ONLY ------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Wisconsin ------------------------------------------------------------------------------- 5 SOLE VOTING POWER None ----------------------------------------------------------------- NUMBER OF 6 SHARED VOTING POWER SHARES BENEFICIALLY 1,533,300 OWNED BY ----------------------------------------------------------------- EACH 7 SOLE DISPOSITIVE POWER REPORTING PERSON None WITH ----------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 1,710,700 ------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,710,700 ------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable ------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 13.1% ------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) CO ------------------------------------------------------------------------------- Page 3 of 15 CUSIP No. 78427V102 13G ------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON ZFIC, Inc. ------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) [_] (see Instructions) (b) [_] Not Applicable ------------------------------------------------------------------------------- 3 SEC USE ONLY ------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Wisconsin ------------------------------------------------------------------------------- 5 SOLE VOTING POWER None ----------------------------------------------------------------- NUMBER OF 6 SHARED VOTING POWER SHARES BENEFICIALLY 1,533,300 OWNED BY ----------------------------------------------------------------- EACH 7 SOLE DISPOSITIVE POWER REPORTING PERSON None WITH ----------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 1,710,700 ------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,710,700 ------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable ------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 13.1% ------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) CO ------------------------------------------------------------------------------- Page 4 of 15 CUSIP No. 78427V102 13G ------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Andrew A. Ziegler ------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) [_] (see Instructions) (b) [_] Not Applicable ------------------------------------------------------------------------------- 3 SEC USE ONLY ------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION U.S.A. ------------------------------------------------------------------------------- 5 SOLE VOTING POWER None ----------------------------------------------------------------- NUMBER OF 6 SHARED VOTING POWER SHARES BENEFICIALLY 1,533,300 OWNED BY ----------------------------------------------------------------- EACH 7 SOLE DISPOSITIVE POWER REPORTING PERSON None WITH ----------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 1,710,700 ------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,710,700 ------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable ------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 13.1% ------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) IN ------------------------------------------------------------------------------- Page 5 of 15 CUSIP No. 78427V102 13G ------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Carlene M. Ziegler ------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) [_] (see Instructions) (b) [_] Not Applicable ------------------------------------------------------------------------------- 3 SEC USE ONLY ------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION U.S.A. ------------------------------------------------------------------------------- 5 SOLE VOTING POWER None ----------------------------------------------------------------- NUMBER OF 6 SHARED VOTING POWER SHARES BENEFICIALLY 1,533,300 OWNED BY ----------------------------------------------------------------- EACH 7 SOLE DISPOSITIVE POWER REPORTING PERSON None WITH ----------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 1,710,700 ------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,710,700 ------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable ------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 13.1% ------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) IN ------------------------------------------------------------------------------- Page 6 of 15 CUSIP No. 78427V102 13G ------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Artisan Funds, Inc. ------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) [_] (see Instructions) (b) [_] Not Applicable ------------------------------------------------------------------------------- 3 SEC USE ONLY ------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Wisconsin ------------------------------------------------------------------------------- 5 SOLE VOTING POWER None ----------------------------------------------------------------- NUMBER OF 6 SHARED VOTING POWER SHARES BENEFICIALLY 959,600 OWNED BY ----------------------------------------------------------------- EACH 7 SOLE DISPOSITIVE POWER REPORTING PERSON None WITH ----------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 959,600 ------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 959,600 ------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable ------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 7.3% ------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) CO ------------------------------------------------------------------------------- Page 7 of 15 Item 1(a) Name of Issuer: SI International, Inc. Item 1(b) Address of Issuer's Principal Executive Offices: 12012 Sunset Hills Road Reston, Virginia 20190-5869 Item 2(a) Name of Person Filing: Artisan Partners Limited Partnership ("Artisan Partners") Artisan Investment Corporation, the general partner of Artisan Partners ("Artisan Corp.") ZFIC, Inc., the sole stockholder of Artisan Corp. ("ZFIC") Andrew A. Ziegler Carlene M. Ziegler Artisan Funds, Inc. ("Artisan Funds") Item 2(b) Address of Principal Business Office: Artisan Partners, Artisan Corp., ZFIC, Mr. Ziegler, Ms. Ziegler and Artisan Funds are all located at: 875 East Wisconsin Avenue, Suite 800 Milwaukee, WI 53202 Item 2(c) Citizenship: Artisan Partners is a Delaware limited partnership Artisan Corp. is a Wisconsin corporation ZFIC is a Wisconsin corporation Mr. Ziegler and Ms. Ziegler are U.S. citizens Artisan Funds is a Wisconsin corporation Item 2(d) Title of Class of Securities: Common Stock Item 2(e) CUSIP Number: 78427V102 Item 3 Type of Person: (d) Artisan Funds is an Investment Company under section 8 of the Investment Company Act. (e) Artisan Partners is an investment adviser registered under section 203 of the Investment Advisers Act of 1940; Artisan Corp. is the general partner of Artisan Partners; ZFIC is the sole stockholder of Artisan Corp.; Mr. Ziegler and Ms. Ziegler are the principal stockholders of ZFIC. Page 8 of 15 Item 4 Ownership (at July 31, 2007): (a) Amount owned "beneficially" within the meaning of rule 13d-3: 1,710,700 (b) Percent of class: 13.1 % (based on 13,106,742 shares outstanding as of May 1, 2007) (c) Number of shares as to which such person has: (i) sole power to vote or to direct the vote: None (ii) shared power to vote or to direct the vote: 1,533,300 (iii) sole power to dispose or to direct the disposition of: None (iv) shared power to dispose or to direct disposition of: 1,710,700 Item 5 Ownership of Five Percent or Less of a Class: Not Applicable Item 6 Ownership of More than Five Percent on Behalf of Another Person: The shares reported herein have been acquired on behalf of discretionary clients of Artisan Partners; as reported herein, Artisan Partners holds 1,710,700 shares, including 959,600 shares on behalf of Artisan Funds. Persons other than Artisan Partners are entitled to receive all dividends from, and proceeds from the sale of, those shares. Item 7 Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person: Not Applicable Item 8 Identification and Classification of Members of the Group: Not Applicable Item 9 Notice of Dissolution of Group: Not Applicable Item 10 Certification: By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. Page 9 of 15 Signature After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. Date: August 9, 2007 ARTISAN INVESTMENT CORPORATION, for itself and as the general partner of ARTISAN PARTNERS LIMITED PARTNERSHIP By: Janet D. Olsen* ----------------------------------------- ZFIC, INC. By: Janet D. Olsen* ----------------------------------------- ANDREW A. ZIEGLER Andrew A. Ziegler* ---------------------------------------------- CARLENE M. ZIEGLER Carlene M. Ziegler* ---------------------------------------------- ARTISAN FUNDS, INC. By: Janet D. Olsen * ----------------------------------------- *By: /s/ Janet D. Olsen ----------------------------------------- Janet D. Olsen Vice President of Artisan Investment Corporation Attorney-in-Fact for ZFIC, Inc. Attorney-in-Fact for Andrew A. Ziegler Attorney-in-Fact for Carlene M. Ziegler General Counsel and Secretary of Artisan Funds, Inc. Page 10 of 15 Exhibit Index Exhibit 1 Joint Filing Agreement dated August 9, 2007 by and among Artisan Partners Limited Partnership, Artisan Investment Corporation, ZFIC, Inc., Andrew A. Ziegler, Carlene M. Ziegler and Artisan Funds, Inc. Exhibit 2 Power of Attorney of ZFIC, Inc., dated March 19, 2007 Exhibit 3 Power of Attorney of Andrew A. Ziegler dated March 19, 2007 Exhibit 4 Power of Attorney of Carlene M. Ziegler dated March 19, 2007 Page 11 of 15 EXHIBIT 1 JOINT FILING AGREEMENT The undersigned hereby agree to the joint filing of the Schedule 13G to which this Agreement is attached. Dated: August 9, 2007 ARTISAN INVESTMENT CORPORATION, for itself and as the general partner of ARTISAN PARTNERS LIMITED PARTNERSHIP By: Janet D. Olsen* ---------------------------------------- ZFIC, INC. By: Janet D. Olsen* ---------------------------------------- ANDREW A. ZIEGLER Andrew A. Ziegler* --------------------------------------------- CARLENE M. ZIEGLER Carlene M. Ziegler* --------------------------------------------- ARTISAN FUNDS, INC. By: Janet D. Olsen * ---------------------------------------- *By: /s/ Janet D. Olsen ---------------------------------------- Janet D. Olsen Vice President of Artisan Investment Corporation Attorney-in-Fact for ZFIC, Inc. Attorney-in-Fact for Andrew A. Ziegler Attorney-in-Fact for Carlene M. Ziegler General Counsel and Secretary of Artisan Funds, Inc. Page 12 of 15 EXHIBIT 2 POWER OF ATTORNEY The undersigned, ZFIC, Inc., hereby appoints Lawrence A. Totsky, Janet D. Olsen, and Sarah A. Johnson, and each of them individually, its true and lawful attorney-in-fact and agent, with full power to execute and file with the United States Securities and Exchange Commission and any stock exchange or similar authority, for and on its behalf in any and all capacities, any and all reports required to be filed pursuant to Section 13 of the Securities Exchange Act of 1934 and the rules thereunder, including but not limited to reports on Schedule 13D or 13G, any and all amendments to such reports, with all exhibits, and any other forms or documents as may be necessary in connection with the filing of such reports with the United States Securities and Exchange Commission and any stock exchange or similar authority, granting unto said attorney full power and authority to do and perform any and all acts for and on behalf of the undersigned which may be necessary or desirable to complete, as fully as the undersigned might or could do in person. This Power of Attorney shall remain in full force and effect until revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact and agents. IN WITNESS WHEREOF the undersigned has caused this Power of Attorney to be executed this 19th day of March, 2007. ZFIC, INC. By: /s/ Andrew A. Ziegler ------------------------------ Andrew A. Ziegler Vice President STATE OF WISCONSIN ) ) SS. COUNTY OF MILWAUKEE ) I, Timothy K. Weston, a Notary Public in and for the County of Milwaukee, State of Wisconsin, DO HEREBY CERTIFY that Andrew A. Ziegler, who is personally known to me to be the same person whose name is subscribed to the foregoing instrument, appeared before me this day in person and acknowledged that he signed and delivered the said instrument as his own free and voluntary act, for the uses and purposes therein set forth. Given under my hand and notarial seal, this 19th day of March, 2007. /s/ Timothy K. Weston ------------------------------ Notary Public Page 13 of 15 EXHIBIT 3 POWER OF ATTORNEY The undersigned, Andrew A. Ziegler, hereby appoints Lawrence A. Totsky, Janet D. Olsen, and Sarah A. Johnson, and each of them individually, his true and lawful attorney-in-fact and agent, with full power to execute and file with the United States Securities and Exchange Commission and any stock exchange or similar authority, for and on his behalf in any and all capacities, any and all reports required to be filed pursuant to Section 13 of the Securities Exchange Act of 1934 and the rules thereunder, including but not limited to reports on Schedule 13D or 13G, any and all amendments to such reports, with all exhibits, and any other forms or documents as may be necessary in connection with the filing of such reports with the United States Securities and Exchange Commission and any stock exchange or similar authority, granting unto said attorney full power and authority to do and perform any and all acts for and on behalf of the undersigned which may be necessary or desirable to complete, as fully as the undersigned might or could do in person. This Power of Attorney shall remain in full force and effect until revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact and agents. IN WITNESS WHEREOF the undersigned has caused this Power of Attorney to be executed this 19th day of March, 2007. /s/ Andrew A. Ziegler ------------------------------ Andrew A. Ziegler STATE OF WISCONSIN ) ) SS. COUNTY OF MILWAUKEE ) I, Timothy K. Weston, a Notary Public in and for the County of Milwaukee, State of Wisconsin, DO HEREBY CERTIFY that Andrew A. Ziegler, who is personally known to me to be the same person whose name is subscribed to the foregoing instrument, appeared before me this day in person and acknowledged that he signed and delivered the said instrument as his own free and voluntary act, for the uses and purposes therein set forth. Given under my hand and notarial seal, this 19th day of March, 2007. /s/ Timothy K. Weston ------------------------------ Notary Public Page 14 of 15 EXHIBIT 4 POWER OF ATTORNEY The undersigned, Carlene M. Ziegler, hereby appoints Lawrence A. Totsky, Janet D. Olsen, and Sarah A. Johnson, and each of them individually, her true and lawful attorney-in-fact and agent, with full power to execute and file with the United States Securities and Exchange Commission and any stock exchange or similar authority, for and on her behalf in any and all capacities, any and all reports required to be filed pursuant to Section 13 of the Securities Exchange Act of 1934 and the rules thereunder, including but not limited to reports on Schedule 13D or 13G, any and all amendments to such reports, with all exhibits, and any other forms or documents as may be necessary in connection with the filing of such reports with the United States Securities and Exchange Commission and any stock exchange or similar authority, granting unto said attorney full power and authority to do and perform any and all acts for and on behalf of the undersigned which may be necessary or desirable to complete, as fully as the undersigned might or could do in person. This Power of Attorney shall remain in full force and effect until revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact and agents. IN WITNESS WHEREOF the undersigned has caused this Power of Attorney to be executed this 19th day of March, 2007. /s/ Carlene M. Ziegler ------------------------------ Carlene M. Ziegler STATE OF WISCONSIN ) ) SS. COUNTY OF MILWAUKEE ) I, Timothy K. Weston, a Notary Public in and for the County of Milwaukee, State of Wisconsin, DO HEREBY CERTIFY that Carlene M. Ziegler, who is personally known to me to be the same person whose name is subscribed to the foregoing instrument, appeared before me this day in person and acknowledged that she signed and delivered the said instrument as her own free and voluntary act, for the uses and purposes therein set forth. Given under my hand and notarial seal, this 19th day of March, 2007. /s/ Timothy K. Weston ------------------------------ Notary Public Page 15 of 15