This first phase of a projected longitudinal study designed to assess the impact of Head Start in Montgomery County, Maryland, concentrates on reporting results of data collection activities from 1966 to the end of 1969. Instruments were developed to measure whether Head Start evolved a curriculum relevant to its goals and whether the developmental characteristics of former Head Starters are different from those of comparable first graders without Head Start experience. Methodology involved observation in classrooms, trial of specially developed materials, and administration of tests. Classroom adjustment was evaluated for pupils working with teachers, with other adults, and without direct adult supervision. Pupils in Head Start classes, former Head Starters currently in kindergarten, and non-Head Starters used as matched controls were tested on tests of basic experience and rated for adjustment. First graders who were former Head Starters were tested on standardized intelligence and readiness tests. Even though few significant differences were found between Head Starters and non-Head Starters, this phase of the study was judged successful because instruments were developed for the description of Head Start classroom activities and for the evaluation of classroom adjustment. Sixteen tables and thirteen figures are provided along with three appendixes. (WY)