Some characteristics of children, their families, the programs they attended, and the relationship of these experiences to their development are covered in this national report on the immediate changes associated with participation in full year Head Start programs. Major emphasis was placed on the child's cognitive and social development in the context of the classroom experience. Data was collected through the use of 24 forms, questionnaires and tests. Major findings were: (1) life circumstances associated with family economic status were associated with the child's performance on measures of cognitive development and achievement upon entering a Head Start Program. (2) There were significant overall gains on cognitive development, preacademic readiness, the ability to learn a new task, and achievement motivation. The gains were greater than expected at usual maturational rates. (3) As age increased, achievement motivation increased and adjustment problems decreased. (4) Teacher demographic variables were not related to the progress of the children. (5) Programs did make a difference and the highly structured focused, and well-implemented compensatory programs brought about greater immediate cognitive gains than low structured, diffuse and less well implemented programs. (6) There was substantial variation in cognitive gains among classes and a significant amount of this variation could be predicted from class and teacher-based observation. (EH)