Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * Cohen Seth B.	2. Date of Event Requiring Statement (MM/DD/YYYY) 1/1/2018	3. Issuer Name and Ticker or Trading Symbol CASTLIGHT HEALTH, INC. [CSLT]
(Last)        (First)        (Middle) C/O CASTLIGHT HEALTH, INC., 150 SPEAR ST., SUITE 400	4. Relationship of Reporting Person(s) to Issuer (Check all applicable) __ X __ Director                            _____ 10% Owner _____ Officer (give title below)          _____ Other (specify below)
(Street) SAN FRANCISCO, CA 94105        (City)              (State)              (Zip)	5. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _ X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Class B Common Stock	124898	D
Class B Common Stock	6375   (1)	D
Class B Common Stock	13125   (2)	D
Class B Common Stock	38672   (3)	D
Class B Common Stock	60000   (4)	D

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Director Stock Option (right to buy)	(5)	2/23/2026	Class B Common Stock	5146	$2.99	D

Explanation of Responses:
(1)	Represents an award of restricted stock units ("RSUs"). The RSUs will vest in equal quarterly installments over one year, beginning on February 17, 2018. Each RSU represents a contingent right to receive one share of the Issuer's Class B common stock upon settlement for no consideration.
(2)	Represents an award of RSUs. The RSUs will vest in equal quarterly installments over two years, beginning on February 15, 2018. Each RSU represents a contingent right to receive one share of the Issuer's Class B common stock upon settlement for no consideration.
(3)	Represents an award of RSUs. The RSUs will vest in equal quarterly installments over three years, beginning on February 16, 2018. Each RSU represents a contingent right to receive one share of the Issuer's Class B common stock upon settlement for no consideration.
(4)	Represents an award of RSUs. 25% of the RSUs will vest on February 16, 2018 and the remainder will vest on each quarterly anniversary thereafter in equal installments. Each RSU represents a contingent right to receive one share of the Issuer's Class B common stock upon settlement for no consideration.
(5)	The shares subject to the stock option will vest in 48 equal monthly installments beginning on January 24, 2018, until such time as the option is 100% vested, subject to the continuing service of the Reporting Person on each vesting date.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Cohen Seth B. C/O CASTLIGHT HEALTH, INC. 150 SPEAR ST., SUITE 400 SAN FRANCISCO, CA 94105	X

Signatures
/s/ Jennifer Chaloemtiarana, by power of attorney		1/3/2018
** Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
*	If the form is filed by more than one reporting person, see Instruction 5(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).
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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.