Registration Nos. 333-144744

811-22099

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	¨
Pre-Effective Amendment No.	¨
Post-Effective Amendment No. 36	x

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940	¨
Amendment No. 40	x

(Check appropriate box or boxes.)

GATEWAY TRUST

(Exact Name of Registrant as Specified in Charter)

399 Boylston Street, Boston, Massachusetts 02116

(Address of principal executive offices) (Zip Code)

Registrant’s Telephone Number, including Area Code (617) 449-2810

Coleen Downs Dinneen, Esq.

NGAM Distribution, L.P.

399 Boylston Street

Boston, Massachusetts 02116

(Name and Address of Agent for Service)

Copy to:

John M. Loder, Esq.

Ropes & Gray

800 Boylston Street

Boston, Massachusetts 02199

Approximate Date of Public Offering

It is proposed that this filing will become effective (check appropriate box):

x Immediately upon filing pursuant to paragraph (b)

¨ On (date) pursuant to paragraph (b)

¨ 60 days after filing pursuant to paragraph (a)(1)

¨ On (date) pursuant to paragraph (a)(1)

¨ 75 days after filing pursuant to paragraph (a)(2)

¨ On (date) pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

¨ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

GATEWAY TRUST

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this registration statement under Rule 485(b) under the Securities Act and has duly caused this Post-Effective Amendment No. 36 to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Boston, and the Commonwealth of Massachusetts on the 21^st day of May, 2015.

GATEWAY TRUST
By:	/s/ David L. Giunta
	David L. Giunta
	President and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, as amended, this amendment to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

/s/ David L. Giunta
David L. Giunta	Trustee, President and Chief Executive Officer	May 21, 2015
/s/ Michael C. Kardok
Michael C. Kardok	Treasurer	May 21, 2015
Robert J. Blanding *
Robert J. Blanding	Trustee	May 21, 2015
Kenneth A. Drucker *
Kenneth A. Drucker	Trustee	May 21, 2015
Edmond J. English *
Edmond J. English	Trustee	May 21, 2015
Richard A. Goglia *
Richard A. Goglia	Trustee	May 21, 2015
John T. Hailer *
John T. Hailer	Trustee	May 21, 2015
Wendell J. Knox *
Wendell J. Knox	Trustee	May 21, 2015

Martin T. Meehan *
Martin T. Meehan	Trustee	May 21, 2015
Sandra O. Moose *
Sandra O. Moose	Trustee, Chairperson of the Board	May 21, 2015
Erik R. Sirri *
Erik R. Sirri	Trustee	May 21, 2015
Peter J. Smail *
Peter J. Smail	Trustee	May 21, 2015
Cynthia L. Walker *
Cynthia L. Walker	Trustee	May 21, 2015

*By:	/s/ Coleen Downs Dinneen
	Coleen Downs Dinneen
	Attorney-In-Fact1
	May 21, 2015

¹  Powers of Attorney for Robert Blanding, John T. Hailer, Sandra O. Moose and Cynthia L. Walker are incorporated by reference to exhibit (q) to the Registration Statement on Form N-1A filed on July 20, 2007. Power of Attorney for Kenneth Drucker is incorporated by reference to exhibit (q)(2) to PEA No. 2 to the Registration Statement filed on April 30, 2009. Power of Attorney for Wendell J. Knox is incorporated by reference to exhibit (q)(3) to PEA No. 3 to the Registration Statement filed on July 2, 2009. Powers of Attorney for Erik Sirri and Peter Smail are incorporated by reference to exhibits (q)(4) and (q)(5) to PEA No. 8 to the Registration Statement filed on December 28, 2009. Powers of Attorney for Martin T. Meehan and Edmond J. English are incorporated by reference to exhibits (q)(8) and (q)(9) to PEA No. 22 to the Registration Statement filed on March 28, 2013. Power of Attorney for Richard A. Goglia is incorporated by reference to exhibit (h)(1)(vii) to PEA No. 33 filed on March 27, 2015.

Gateway Trust

Exhibit Index

Exhibits for Item 28 of Form N-1A

Exhibit	Exhibit Description
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase