UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 21)

CLINICAL DATA, INC.

(Name of Issuer)

COMMON STOCK, $.01 par value per share

(Title of Class of Securities)

18725U109

(CUSIP Number)

Third Security, LLC

The Governor Tyler

1881 Grove Avenue

Radford, Virginia 24141

Attention:  Marcus E. Smith, Esq.

Telephone No.:  540-633-7971

(Name, Address and Telephone Number of Person Authorized to

Receive Notices and Communications)

Copy to:

John Owen Gwathmey, Esq.

Troutman Sanders LLP

Troutman Sanders Building

1001 Haxall Point

Richmond, Virginia 23219

September 26, 2008

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement

on Schedule 13G to report the acquisition which is the

subject of this Schedule 13D, and is filing this

schedule because of Rules 13d-1(e), (f) or (g),

check the following box £.

CUSIP NO.  18725U109 13D Page 2 of 12 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)    Randal J. Kirk
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP			(a)           ¨ (b)           þ
3	SEC USE ONLY
4	SOURCE OF FUNDS    PF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)			¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION    United States
NUMBER OF		7	SOLE VOTING POWER    2,063,458
SHARES BENEFICIALLY		8	SHARED VOTING POWER    8,914,224
OWNED BY EACH REPORTING		9	SOLE DISPOSITIVE POWER    2,063,458
PERSON WITH		10	SHARED DISPOSITIVE POWER    8,914,224
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    10,977,682
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    48.4%
14	TYPE OF REPORTING PERSON    IN

CUSIP NO.  18725U109 13D Page 3 of 12 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)    RJK, L.L.C.                                                                I.R.S. Identification No.:  54-1816015
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP			(a)           ¨ (b)           þ
3	SEC USE ONLY
4	SOURCE OF FUNDS    WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)			¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION    Virginia
NUMBER OF		7	SOLE VOTING POWER    0
SHARES BENEFICIALLY		8	SHARED VOTING POWER    1,096,624
OWNED BY EACH REPORTING		9	SOLE DISPOSITIVE POWER    0
PERSON WITH		10	SHARED DISPOSITIVE POWER    1,096,624
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    1,096,624
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    4.8%
14	TYPE OF REPORTING PERSON    OO – limited liability company

CUSIP NO.  18725U109 13D Page 4 of 12 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)    New River Management II, LP                               I.R.S. Identification No.:  65-1166473
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP			(a)           ¨ (b)           þ
3	SEC USE ONLY
4	SOURCE OF FUNDS    WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)			¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION    Virginia
NUMBER OF		7	SOLE VOTING POWER    0
SHARES BENEFICIALLY		8	SHARED VOTING POWER    1,049,877
OWNED BY EACH REPORTING		9	SOLE DISPOSITIVE POWER    0
PERSON WITH		10	SHARED DISPOSITIVE POWER    1,049,877
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    1,049,877
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    4.6%
14	TYPE OF REPORTING PERSON    OO – limited partnership

CUSIP NO.  18725U109 13D Page 5 of 12 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)    Kirkfield, L.L.C.                                                         I.R.S. Identification No.:  54-1725089
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP			(a)           ¨ (b)           þ
3	SEC USE ONLY
4	SOURCE OF FUNDS    WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)			¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION    Virginia
NUMBER OF		7	SOLE VOTING POWER    0
SHARES BENEFICIALLY		8	SHARED VOTING POWER    1,626,722
OWNED BY EACH REPORTING		9	SOLE DISPOSITIVE POWER    0
PERSON WITH		10	SHARED DISPOSITIVE POWER    1,626,722
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,626,722
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    7.2%
14	TYPE OF REPORTING PERSON    OO – limited liability company

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)    New River Management V, LP                               I.R.S. Identification No.:  56-2652938
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP			(a)           ¨ (b)           þ
3	SEC USE ONLY
4	SOURCE OF FUNDS    WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)			¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION    Delaware
NUMBER OF		7	SOLE VOTING POWER    0
SHARES BENEFICIALLY		8	SHARED VOTING POWER    3,380,985
OWNED BY EACH REPORTING		9	SOLE DISPOSITIVE POWER    0
PERSON WITH		10	SHARED DISPOSITIVE POWER    3,380,985
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 3,380,985
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    14.9%
14	TYPE OF REPORTING PERSON    OO – limited partnership

Page 6 of 12 Pages

This Amendment No. 21 (the “Amendment”) amends and supplements the Statement on Schedule 13D, dated November 26, 1999 and filed on December 6, 1999, as amended by Amendment No. 1 dated March 10, 2000 and filed on March 15, 2000, Amendment No. 2 dated June 8, 2000 and filed on June 9, 2000, Amendment No. 3 dated December 31, 2000 and filed on January 8, 2001, Amendment No. 4 dated February 7, 2001 and filed on March 1, 2001, Amendment No. 5 dated June 6, 2001 and filed on June 8, 2001, Amendment No. 6 dated June 25, 2001 and filed on June 26, 2001, Amendment No. 7 dated September 6, 2001 and filed on September 7, 2001, Amendment No. 8 dated October 23, 2001 and filed on October 26, 2001, Amendment No. 9 dated October 26, 2001 and filed on October 30, 2001, Amendment No. 10 dated August 21, 2002 and filed on August 21, 2002, Amendment No. 11 dated April 29, 2003 and filed on May 2, 2003, Amendment No. 12 dated November 10, 2003 and filed on November 14, 2003, Amendment No. 13 dated June 20, 2005 and filed on June 27, 2005, Amendment No. 14 dated November 17, 2005 and filed on November 23, 2005, Amendment No. 15 dated February 9, 2006 and filed on February 15, 2006, Amendment No. 16 dated May 18, 2006 and filed on May 23, 2006, Amendment No. 17 dated June 13, 2006 and filed on June 15, 2006, Amendment No. 18 dated September 13, 2006 and filed on September 22, 2006, Amendment No. 19 dated February 26, 2007 and filed on February 27, 2007, and Amendment No. 20 dated July 17, 2007 and filed on July 20, 2007 (as amended, the “Original Schedule 13D”), relating to the Common Stock, par value $.01 per share (the “Common Stock”), of Clinical Data, Inc., a Delaware corporation (the “Issuer”).  Mr. Randal J. Kirk (“Mr. Kirk”), RJK, L.L.C., a Virginia limited liability company (“RJK”), New River Management II, LP, a Virginia limited partnership (“NRM II”), Kirkfield, L.L.C., a Virginia limited liability company (“Kirkfield”), and New River Management V, LP, a Delaware limited partnership (“NRM V” and, together with Mr. Kirk, RJK, NRM II and Kirkfield, the “Reporting Persons”), are filing this Amendment to disclose the acquisition by Mr. Kirk, Kirkfield, Zhong Mei, L.L.C., a Virginia limited liability company (“Zhong Mei”), Randal J Kirk (2000) Limited Partnership, a Delaware limited partnership (“RJK 2000”), Third Security Senior Staff 2008 LLC, a Virginia limited liability company (“Senior Staff 2008”), Third Security Staff 2008 LLC, a Virginia limited liability company (“Staff 2008”), and Third Security Incentive 2008 LLC, a Virginia limited liability company (“Incentive 2008”), of an aggregate of 1,514,922 shares in a private placement by the Issuer on September 26, 2008 (the “Offering”).  As described in this Amendment, some of the Common Stock that is beneficially owned by Mr. Kirk is directly beneficially owned by one of the following entities, each of which is controlled by Mr. Kirk: RJK, Kirkfield, RJK 2000, Third Security Staff 2001 LLC, a Virginia limited liability company (“Staff 2001”), Senior Staff 2008, Staff 2008, Incentive 2008, NRM II, New River Management III, LP, a Virginia limited partnership (“NRM III”), NRM V, Zhong Mei and Radford Investment Limited Partnership, a Delaware limited partnership (“Radford”).

Except as set forth below, there are no changes to the information set forth in the Original Schedule 13D.

Item 3. Source and Amount of Funds or Other Consideration.

Item 3 of the Original Schedule 13D is hereby amended and supplemented as follows:

Page 7 of 12 Pages

“On September 26, 2008, Mr. Kirk, Kirkfield, Zhong Mei, RJK 2000, Senior Staff 2008, Staff 2008 and Incentive 2008 invested $25 million of cash on hand to purchase an aggregate of 1,514,922 shares of Common Stock at a price of $16.5025 per share in the Offering.”

Item 5. Interest in Securities of the Issuer.

Item 5(a) of the Original Schedule 13D is hereby amended and restated to read in its entirety as follows:

“The aggregate number and percentage of shares of Common Stock to which this statement relates is 10,977,682 shares, representing 48.4% of the 22,674,320 shares outstanding as of the date of this report, based upon the number of shares disclosed by the Issuer as of July 31, 2008 in the Issuer’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2008 (the most recent available filing by the Issuer with the Securities and Exchange Commission) and taking into account the 1,514,922 shares issued in the Offering.  Mr. Kirk directly beneficially owns 2,063,458 of the shares to which this report relates.  The remaining 8,914,224 shares of Common Stock to which this statement relates are directly beneficially owned as follows:

Owner	Shares
Kirkfield	1,626,722
RJK	1,096,624
RJK 2000	242,388
Zhong Mei	183,772
NRM II	1,049,877
NRM III	290,014
NRM V	3,380,985
Radford	230,029
Staff 2001	692,617
Senior Staff 2008	48,478
Staff 2008	48,478
Incentive 2008	24,240

Mr. Kirk could be deemed to have indirect beneficial ownership of the shares directly beneficially owned by Kirkfield, RJK, RJK 2000, Zhong Mei, NRM II, NRM III, NRM V, Radford, Staff 2001, Senior Staff 2008, Staff 2008 and Incentive 2008.  As of the date hereof, each of RJK and NRM II owns less than 5% of the outstanding Common Stock of the Issuer and is no longer a reporting person for purposes of Schedule 13D.”

Item 5(c) of the Original Schedule 13D is hereby amended and supplemented as follows:

“Other than the purchase of Common Stock in the Offering as reported herein and the issuance of shares of Common Stock in connection with Mr. Kirk’s service to the Issuer as the Chairman of the Board, the only transaction in which the Reporting Persons have engaged in shares of Common Stock since the filing of Amendment No. 20 with the Securities and Exchange Commission on July 20, 2007 is the open market purchase of 5,985 shares by NRM V on June 20, 2008 for a purchase price of $16.49 per share.”

Page 8 of 12 Pages

Item 6.            Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.

Item 6 of the Original Schedule 13D is hereby amended and supplemented as follows:

“In connection with the purchase in the private placement of Common Stock, the Issuer issued 212,089, 302,983, 60,597, 121,194, 24,239, 24,239 and 12,120 warrants to Mr. Kirk, Kirkfield, Zhong Mei, RJK 2000, Senior Staff 2008, Staff 2008 and Incentive 2008, respectively.  The exercise price of the warrants is $16.44, equaling the closing bid price of the Common Stock on the Nasdaq Stock Market on September 26, 2008.  The warrants are exercisable at any time six months after September 26, 2008 through the close of business on the fifth year anniversary of the date on which the warrants initially become exercisable.  The form of Common Stock Purchase Warrant is filed herewith as Exhibit 4.1.  Except as otherwise described in this statement, to the best knowledge of any of the Reporting Persons, there are no contracts, arrangements, understandings or relationships (legal or otherwise) among the persons named in Item 2, or between such persons and any other person, with respect to any securities of the Issuer, including, but not limited to, transfer or voting of any of the securities, finder's fees, joint ventures, loan or option arrangements, puts or calls, guarantees of profits, division of profits or loss, or the giving or withholding of proxies.”

Item 7. Material to be Filed as Exhibits.

The following documents are being filed as exhibits to this Amendment and are incorporated herein by reference:

Exhibit 4.1 Form of Common Stock Purchase Warrant

Exhibit 99.1 Joint Filing Agreement, dated as of September 30, 2008, by and among Randal J. Kirk, RJK, L.L.C., New River Management II, LP, Kirkfield, L.L.C. and New River Management V, LP

Page 9 of 12 Pages

SIGNATURE

After reasonable inquiry and to the best of their knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

Date:  September 30, 2008	/s/ Randal J. Kirk
	Randal J. Kirk
Date:  September 30, 2008	RJK, L.L.C.
	By:	Third Security, LLC, its managing member
	By:	/s/ Randal J. Kirk
		Randal J. Kirk
		Sole Member
Date:  September 30, 2008	NEW RIVER MANAGEMENT II, LP
	By:	Third Security Capital Partners, LLC, its general partner
	By:	Third Security, LLC, its managing member
	By:	/s/ Randal J. Kirk
		Randal J. Kirk
		Sole Member
Date:  September 30, 2008	KIRKFIELD, L.L.C.
	By:	Third Security, LLC, its managing member
	By:	/s/ Randal J. Kirk
		Randal J. Kirk
		Sole Member

Page 10 of 12 Pages

Date:  September 30, 2008	NEW RIVER MANAGEMENT V, LP
	By:	Third Security Capital Partners V, LLC, its general partner
	By:	Third Security, LLC, its managing member
	By:	/s/ Randal J. Kirk
		Randal J. Kirk
		Manager

Page 11 of 12 Pages

EXHIBIT INDEX

Exhibit Number Exhibit

Exhibit 4.1 Form of Common Stock Purchase Warrant

Exhibit 99.1 Joint Filing Agreement, dated as of September 30, 2008, by and among Randal J. Kirk, RJK, L.L.C., New River Management II, LP, Kirkfield, L.L.C. and New River Management V, LP

Page 12 of 12 Pages