UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13D/A
Under the Securities Exchange Act of 1934
(Amendment No. 1)*
FLEX PHARMA, INC. 
(Name of Issuer)
Common Stock, par value $0.0001 per share 
(Title of Class of Securities)
33938A105
(CUSIP Number)
Boston Foundation, Inc.
George C. Wilson, Assistant Treasurer
75 Arlington Street Boston, MA 02116
617-338-1626
george.wilson@tbf.org
(Name, Address and Telephone Number of Person Authorized to 
Receive Notices and Communications)
January 16, 2019
(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 that is the subject of 
this Schedule 13D, and is filing this schedule because of Rule 
240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the 
following box. /__ /
NOTE: Schedules filed in paper format shall include a signed 
original and five copies of the schedule, including all 
exhibits. See Rule 13d-7 for other parties to whom copies are to 
be sent.
*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 disclosures 
provided in a prior cover page.
The information required on 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).
CUSIP No. 33938A105
(1) Names of reporting persons 
Boston Foundation, Inc.
(2) Check the appropriate box if a member of a group (see 
instructions)
(a)	
(b)	
(3) SEC use only
(4) Source of funds (see instructions) OO
(5) Check if disclosure of legal proceedings is required 
pursuant to Items 2(d) or 2(e)
(6) Citizenship or place of organization MA
Number of shares beneficially owned by each reporting person 
with:
(7) Sole voting power 814,000
(8) Shared voting power
(9) Sole dispositive power 814,000
(10) Shared dispositive power 
(11) Aggregate amount beneficially owned by each reporting 
person 814,000 shares 
(12) Check if the aggregate amount in Row (11) excludes certain 
shares (see instructions)
(13) Percent of class represented by amount in Row (11) 4.5%
(14) Type of reporting person (see instructions) CO
Introduction
This Amendment No. 1 to Schedule 13D (this "Amendment") amends 
the statement on Schedule 13D filed with the Securities and 
Exchange Commission ("SEC") on December 28, 2018 (the "Original 
Schedule 13D") by Boston Foundation, Inc. ("Reporting Person") 
with respect to shares of the common stock, par value $0.0001 
per share of Flex Pharma, Inc. ("Issuer"). The Amendment is 
filed to report the completion of the sale of 1,386,000 shares 
of the Common Stock of the Issuer which resulted in the 
Reporting Person holding less than 5% of the outstanding common 
stock of the Issuer and ceasing to be a reporting person under 
Section 13(d) of the Securities Exchange Act of 1934, as 
amended. Except as expressly set forth herein, this Amendment 
does not modify any of the information set forth in the Original 
Schedule 13D. Capitalized terms used in this Amendment and not 
otherwise defined are used with the meanings given such terms in 
the Original Schedule 13D.
Item 5. Interest in Securities of the Issuer. (a) The Reporting 
Person acquired 2,200,000 shares of the Common Stock of the 
Issuer, or 12.18% of the outstanding shares of Common Stock, 
calculated based on 18,069,476 shares of Common Stock 
outstanding as of October 31, 2018, as reported by the Issuer on 
its Quarterly Report on Form 10-Q for the quarter ended 
September 30, 2018, filed with the Securities and Exchange 
Commission. As described in the Original Schedule 13D, the 
Reporting Person has engaged in open market sales of the shares 
through a registered broker/dealer. As of January 16, 2019,
the Reporting Person owns beneficially and of record 
814,000 shares of Common Stock, or 4.5% of the outstanding shares 
of Common Stock.
(b) The Reporting Person has the sole power to vote or to direct 
the vote, and the sole power to dispose or to direct the 
disposition all 814,000 of the shares of Common Stock of the 
Issuer it owns as of January 16, 2019. The Reporting Person's 
executive officers have the power to determine the timing of the 
sale of the Common Stock of the Issuer by the Reporting Person.
(c)	Since the receipt by the Reporting Person of the gift of the 
2,200,000 shares of the Common Stock of the Issuer on December 
20, 2018, the Reporting Person has engaged in open market sales 
of the Common Stock to provide funds for use in furtherance of 
the charitable purpose and mission of the Reporting Person.
(d)	No person other than the Reporting Person is known to have 
the right to receive or the power to direct the receipt of 
dividends from, or the proceeds from the sale of, the shares of 
Common Stock of the Issuer held by the Reporting Person.
(e)	Reporting Person files this Amendment to report that it has 
ceased to be the beneficial owner of more than five percent of 
the Common Stock of the Issuer.
Signature. After reasonable inquiry and to the best of my 
knowledge and belief, I certify that the information set forth 
in this Amendment is true, complete and correct.
Date: January 17, 2019
Boston Foundation, Inc.
By: /s/ George C. Wilson
George C. Wilson
Title: Assistant Treasurer
ATTENTION: Intentional misstatements or omissions of fact 
constitute Federal criminal violations (See 18 U.S.C. 1001).