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

OMB APPROVAL OMB Number: 3235-0287 Expires: January 31, 2005 Estimated average burden hours per response... 0.5

(Print or Type Responses)

1. Name and Address of Reporting Person * MAVERICK CAPITAL LTD   2. Issuer Name and Ticker or Trading Symbol CASTLIGHT HEALTH, INC. [CSLT] 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) 300 CRESCENT COURT, 18TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 07/12/2017 (Street) DALLAS, TX 75201 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 Class B Common Stock 07/12/2017   C   517,358 (1) A $ 0 1,739,167 I See footnote (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
	Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.		SEC 1474 (9-02)

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

Class A Common Stock

$ 0

07/12/2017

C

517,358 (1)

(1)

(1)

Class B Common Stock

517,358

$ 0

7,216,028

I

See footnote (2)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MAVERICK CAPITAL LTD 300 CRESCENT COURT 18TH FLOOR DALLAS, TX 75201		X
MAVERICK CAPITAL MANAGEMENT LLC 300 CRESCENT COURT 18TH FLOOR DALLAS, TX 75201		X
AINSLIE LEE S III 767 FIFTH AVENUE 11TH FLOOR NEW YORK, NY 10153		X
Warford Andrew Held 300 CRESCENT COURT 18TH FLOOR DALLAS, TX 75201		X

Signatures

/s/ John T. McCafferty, Attorney-in-Fact		07/14/2017
**Signature of Reporting Person		Date
/s/ John T. McCafferty, Attorney-in-Fact		07/14/2017
**Signature of Reporting Person		Date
/s/ John T. McCafferty, Attorney-in-Fact		07/14/2017
**Signature of Reporting Person		Date
/s/ John T. McCafferty, Attorney-in-Fact		07/14/2017
**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)	Each share of Class A Common Stock is convertible into one share of Class B Common Stock without payment of any additional consideration.
(2)	Maverick Capital, Ltd. ("Maverick Capital") is a registered investment adviser under the Investment Advisers Act of 1940, as amended, and acts as the investment manager for each of the portfolio funds for which David B. Singer holds the RSUs and that directly hold the remaining reported securities. Maverick Capital Management, LLC ("Maverick Management") is the general partner of Maverick Capital. Lee S. Ainslie III is the manager of Maverick Management. Andrew H. Warford serves as the Chairman of the Stock Committee of Maverick Capital. Each reporting owner disclaims beneficial ownership of the reported securities except to the extent of its pecuniary interest therein.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.