Media Source Inc. (MSI) is an American company based in Plain City, Ohio.

It began in 1980 as Pages and changed its name in March 1999.

[1] It owns Horn Book, including The Horn Book Magazine, Junior Library Guild, Library Hotline, Library Journal (acquired in 2010),[2] and School Library Journal (acquired in 2010),[2] and Digital Shift.

[3] All of these holdings are under its subsidiary MSI Information Services, the primary trade name under which the company does business.

[4] This article about a United States publishing company is a stub.