UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

o

Rule 13d-1(b)

x

Rule 13d-1(c)

o

Rule 13d-1(d)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

C/R CDM Holdings II, L.P.

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,192,723

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,192,723

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,192,723

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)
6.8%

12.

Type of Reporting Person (See Instructions)
PN (Limited Partnership)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

Carlyle/Riverstone Energy Partners II, L.P.

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
PN (Limited Partnership)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

C/R Energy GP II, LLC

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
OO (Limited Liability Company)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

TC Group Investment Holdings, L.P.

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
PN (Limited Partnership)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

TCG Holdings II, L.P.

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
PN (Limited Partnership)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

DBD Investors V, L.L.C.

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
OO (Limited Liability Company)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

Riverstone Investment Services LLC

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
IA OO (Limited Liability Company)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

Riverstone Holdings LLC

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
OO (Limited Liability Company)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

Carlyle Investment Management L.L.C.

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
IA, OO (Limited Liability Company)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

TC Group, L.L.C.

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
OO (Limited Liability Company)

CUSIP No. 75885Y 107

1.

Names of Reporting Persons
I.R.S. Identification Nos. of Above Persons (Entities Only)

TCG Holdings, L.L.C.

2.

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

(a)

o

(b)

x

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
0

6.

Shared Voting Power
4,875,259

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
4,875,259

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
4,875,259

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)
7.9%

12.

Type of Reporting Person (See Instructions)
OO (Limited Liability Company)

CUSIP No. 75885Y 107

Item 1(a).

Name of Issuer:

Regency Energy Partners LP

Item 1(b).

Address of Issuer’s Principal Executive Offices:
1700 Pacific Avenue, Suite 2900

Dallas, Texas 75201

(214) 750-1771

Item 2(a).

Name of Person Filing:

CUSIP No. 75885Y 107

Item 2(b).

Address of Principal Business Office or, if none, Residence:

Item 2(c).

Citizenship:

Item 2(d).

Title of Class of Securities:

Item 2(e).

CUSIP Number:

Item 3.

If this statement is filed pursuant to Rule 13d-1(b) or 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 Rule 13d-1(b)(1)(ii)(E);

(f)

o

An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F);

(g)

o

A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G);

(h)

o

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

CUSIP No. 75885Y 107

(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

A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J);

(k)

o

Group, in accordance with § 13d-1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:

Item 4.

Ownership.

Holdings:

(a)

Amount beneficially owned:   

4,192,723

(b)

Percent of class:   

6.8%

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote:   

0

(ii)

Shared power to vote or to direct the vote:    

4,192,723

(iii)

Sole power to dispose or to direct the disposition of:   

0

(iv)

Shared power to dispose or to direct the disposition of:   

4,192,723

(a)

Amount beneficially owned:   

4,875,259

(b)

Percent of class:   

7.9%

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote:

0

(ii)

Shared power to vote or to direct the vote:

4,875,259

(iii)

Sole power to dispose or to direct the disposition of:

0

(iv)

Shared power to dispose or to direct the disposition of:

4,875,259

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

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.

The information set forth in response to Item 2 is incorporated herein by reference. 

Item 8.

Identification and Classification of Members of the Group.

Not applicable.

Item 9.

Notice of Dissolution of Group.

Not applicable.

Item 10.

Certifications.

By signing below, I certify that, to the best of my knowledge and belief, the securities referred to above 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.

CUSIP No. 75885Y 107

CUSIP No. 75885Y 107

CUSIP No. 75885Y 107