The Philadelphia Prekindergarten Head Start Program is a child development program for three- and four-year old children from low-income families funded through the Philadelphia Anti-Poverty Action Commission. The approach stresses an interacting and multidisciplinary attempt to improve the child's physical and emotional health, his family relationships, and his abilities to function better as a person. The program has been designed to implement five different early childhood education models: Behavioral Analysis, Bank Street, Montessori, Responsive Learning, and Curriculum for Social and Emotional Development. Programming according to model specifications remained the theoretical basis for daily operation. Research and evaluation activities during 1974-75 have centered around the program's goals for children. They have included classroom observations, the development of forms to assess the extent of model implementation, summarizing and analyzing the results of the Denver Developmental Screening Test, and the inclusion of the children in the Early Childhood Longitudinal File. There was found to be a wide range of practices in terms (1) extent of model implementation, (2) classroom differences within a model, (3) grouping practices, (4) frequency of parent volunteers, and (5) provisioning. Observation data yielding the above information are summarized according to model and across the total program. (RC)