Many profoundly retarded children continue to crawl even though they can walk. Crawling and walking were viewed as two alternative response modes, both reinforced by movement. Children choose the one mode that is easier and faster for them. A training program was designed to increase the ease and speed of walking relative to that of crawling, and consisted of restraint-for-crawling and priming-of-walking. With the program, four retarded children reduced crawling and began to walk instead. When training was discontinued, two children with moderate walking impairment continued to walk rather than crawl. Two children with severe impairment of walking, however, required the occasional use of the restraint procedure to maintain walking as the dominant mode of locomotion. The program was easily administered, required little time, and was effective for all four children.