Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
RA CAPITAL MANAGEMENT, LLC
   2. Issuer Name and Ticker or Trading Symbol
Aclaris Therapeutics, Inc. [ACRS] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
C/O RA CAPITAL MANAGEMENT, LLC, 20 PARK PLAZA, SUITE 1200		 3. Date of Earliest Transaction (Month/Day/Year)
10/28/2015
(Street)

BOSTON, MA 02116		 4. If Amendment, Date Original Filed(Month/Day/Year)
 6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)		 4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)		 7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 10/28/2015   P   149,200 A $ 14 2,469,552 I See Footnote (1)
Common Stock 10/29/2015   P   95,000 A $ 14 2,564,552 (2) I See Footnote (1)

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)		 5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)		 6. Date Exercisable and Expiration Date
(Month/Day/Year)		 7. Title and Amount of Underlying Securities
(Instr. 3 and 4)		 8. Price of Derivative Security
(Instr. 5)		 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)		 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)		 11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
RA CAPITAL MANAGEMENT, LLC
C/O RA CAPITAL MANAGEMENT, LLC
20 PARK PLAZA, SUITE 1200
BOSTON, MA 02116		     X    
Kolchinsky Peter
C/O RA CAPITAL MANAGEMENT, LLC
20 PARK PLAZA, SUITE 1200
BOSTON, MA 02116		     X    
RA Capital Healthcare Fund LP
C/O RA CAPITAL MANAGEMENT, LLC
20 PARK PLAZA, SUITE 1200
BOSTON, MA 02116		     X    

Signatures

 /s/ Peter Kolchinsky, Manager of RA Capital Management, LLC   10/30/2015
**Signature of Reporting Person Date
 /s/ Peter Kolchinsky, individually   10/30/2015
**Signature of Reporting Person Date
 /s/ Peter Kolchinsky, Manager of RA Capital Management, LLC, the General Partner of RA Capital Healthcare Fund, L.P.   10/30/2015
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) The Adviser and Mr. Kolchinsky disclaim beneficial ownership of the reported securities for purposes of Rule 16a-1(a)(1) under the Exchange Act in reliance on Rule 16a-1(a)(1)(v) and (vii), respectively, and therefore disclaim any obligation to report ownership of or transactions in the reported securities under Section 16a of the Exchange Act. The filing of this Form 4 shall not be construed as an admission that either the Adviser or Mr. Kolchinsky is or was, for purposes of Section 16 of the Securities Exchange Act of 1934, the beneficial owner of any of the securities reported herein.
(2) The reported securities are owned by RA Capital Healthcare Fund, L.P. (the "Fund") and an account owned by Blackwell Partners, LLC (the "Blackwell Account"). Following the reported transactions, the Fund held 2,146,914 shares and the Blackwell Account held 417,638 shares. RA Capital Management, LLC (the "Adviser") is the general partner of the Fund and the investment adviser of the Blackwell Account. Peter Kolchinsky is the sole manager of the Adviser. In their respective capacities, each of Mr. Kolchinsky and the Adviser may be deemed to beneficially own the reported securities for purposes of Section 13(d) of the Exchange Act.

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