The films were sold at camera shops, in department stores, and by mail order catalog.
Castle obtained home-movie rights to cartoons from several animation studios, including Terrytoons (1938), Ub Iwerks (1941), and Walter Lantz (1947). During World War II it produced numerous documentary and training films for the U.S. armed services.
In 1947, United World Films, Inc., the non-theatrical division of Universal Pictures, purchased a majority stake in Castle Films. Castle subsequently became a Universal subsidiary, drawing upon the studio's library of vintage films (with Abbott and Costello, W. C. Fields, Boris Karloff, James Stewart, etc.). Castle Films changed its name to Universal 8 in 1977, but the era of home video brought an end to Universal's home-movie enterprise in 1984.
The complete inventory of Castle Films (more than 1000 titles over 40 years) is listed in Scott MacGillivray's book Castle Films: A Hobbyist's Guide, ISBN 0-595-32491-6.