UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

o

Rule 13d-1(b)

o

Rule 13d-1(c)

ý

Rule 13d-1(d)

CUSIP No. 904311107

1.

Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only)
Rosewood Capital IV, L.P.

22-3707169

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
3,371,403

6.

Shared Voting Power 
0

7.

Sole Dispositive Power 
3,371,403

8.

Shared Dispositive Power
0

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
3,371,403

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
10.65%*

12.

Type of Reporting Person (See Instructions)
PN

CUSIP No. 904311107

1.

Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only)
Rosewood Capital Associates IV, L.L.C.

22-3707171

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
3,624,165*

6.

Shared Voting Power 
0

7.

Sole Dispositive Power 
3,624,165*

8.

Shared Dispositive Power
0

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
3,624,165*

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
11.45%**

12.

Type of Reporting Person (See Instructions)
OO

Item 1.

(a)

Name of Issuer
Under Armour, Inc.

(b)

Address of Issuer’s Principal Executive Offices
1020 Hull Street, 3rd Floor, Baltimore, MD  21230.

Item 2.

(a)

Name of Person Filing
Rosewood Capital IV, L.P. and Rosewood Capital Associates IV, L.L.C.

(b)

Address of Principal Business Office or, if none, Residence
One Maritime Plaza #1401, San Francisco, CA  94111

(c)

Citizenship
See the responses to Item 4 on the attached cover pages.

(d)

Title of Class of Securities
Class A Common Stock, $0.0003-1/3 par value per share

(e)

CUSIP Number
904311107

Item 3.

If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

o

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).

(b)

o

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

(c)

o

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).

(d)

o

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C 80a-8).

(e)

o

An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)

o

An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)

o

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

o

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

o

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

o

Group, in accordance with §240.13d-1(b)(1)(ii)(J).

Not applicable.

Item 4.

Ownership

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

(a)

Amount beneficially owned:   

See the responses to Item 9 on the attached cover pages.

(b)

Percent of class:   

See the responses to Item 11 on the attached cover pages.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote   

See the responses to Item 5 on the attached cover pages.

(ii)

Shared power to vote or to direct the vote    

See the responses to Item 6 on the attached cover pages.

(iii)

Sole power to dispose or to direct the disposition of   

See the responses to Item 7 on the attached cover pages.

(iv)

Shared power to dispose or to direct the disposition of   

See the responses to Item 8 on the attached cover pages.

Item 5.

Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following   o.

Not applicable.

Item 6.

Ownership of More than Five Percent on Behalf of Another Person

Not applicable.

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

Not applicable.

DATED: March 1, 2006

ROSEWOOD CAPITAL IV, L.P.

By:

Rosewood Capital Associates IV, L.L.C.

Its:

General Partner

By

/s/ Kevin Reilly

Name:  Kevin Reilly

Title:  Managing Member

ROSEWOOD CAPITAL ASSOCIATES IV, L.L.C.

By

/s/ Kevin Reilly

Name:  Kevin Reilly

Title:  Managing Member

DATED: March 1, 2006

ROSEWOOD CAPITAL IV, L.P.

By:

Rosewood Capital Associates IV, L.L.C.

Its:

General Partner

By

/s/ Kevin Reilly

Name:  Kevin Reilly

Title:  Managing Member

ROSEWOOD CAPITAL ASSOCIATES IV, L.L.C.

By

/s/ Kevin Reilly

Name:  Kevin Reilly

Title:  Managing Member