EX-99.906CERT

CERTIFICATION

PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the shareholder report of American Century World Mutual Funds, Inc. (the "Registrant") on Form N-CSR for the period ending May 31, 2011 (the "Report"), we, the undersigned, certify, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1) The Report fully complies with the requirements of Section 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Registrant.

Date:	July 29, 2011
		By:	/s/ Jonathan S. Thomas
			Jonathan S. Thomas
			President
			(chief executive officer)
		By:	/s/ Robert J. Leach
			Robert J. Leach
			Vice President, Treasurer, and
			Chief Financial Officer
			(chief financial officer)