In 1977, a longitudinal study was initiated to assess the effectiveness of health services provided by Head Start. The study provided for 10 domains: pediatric health examinations, health history recordings, dental evaluation, anthropometric assessment, diet and nutrition assessment, and hematology evaluations, as well as for developmental, speech, vision, and hearing evaluations. This report in two volumes presents evaluation findings and technical information related to the study. Volume I, chapter one provides an executive summary including a description of the evaluation project highlights of findings for major evaluation questions, and a detailed summary of findings for each of 10 health services mandated by Head Start performance standards. Chapter two continues with additional detailed descriptions of the Head Start health services. Remaining chapters discuss findings in each of the 10 health domains. Specifically, chapters three through eleven begin with definitions of the health measures and provide background information on their use in collecting data on preschool children. Subsequent sections describe approaches taken in the analysis of the health data, and the final sections present evaluation findings. The appendix to Volume I includes a description of the evaluation methodology and a reference guide to the report and its findings. Volume II contains (1) general appendices listing Head Start performance standards and giving information for interpreting tables of regression results and (2) technical appendices focusing on implementation of the evaluation design; statistics and methodology; description of the Head Start programs, sites, and samples of children; and other relevant materials. (RH)