In October 1969 and again six months later, in April 1970, the Bettye Caldwell Preschool Inventory was administered to Head Start children in Los Angeles County. In all, 704 pre- and post-tests were obtained. The purpose of the testing was to assess one of the goals of the Head Start Program: to enrich the experience of preschool children and to develop those cognitive and social skills which are regarded as essential to success in school. The results showed that, as measured by the Bettye Caldwell Test, Head Start for Los Angeles County was an effective program for developing those skills which are regarded as essential to success in school. The gains are clearly evident in the comparison of pre- and post-test means, in the shifting of the means to higher percentiles on the lower and middle class norms, and on the steady increase in the means with increasing attendance in the program. (Author)