AN ATTEMPT TO ASSESS STIMULUS CONDITIONS IN THE ENVIRONMENT OF THE INFANT IN THE FIRST YEAR OF LIFE AND THE IMPACT OF THESE STIMULI ON HIS ADAPTIVE AND SOCIAL BEHAVIORS WAS PRESENTED. INFANTS WERE OBSERVED IN FOUR CHILD-REARING ENVIRONMENTS--RESIDENTIAL, KIBBUTZ, SINGLE-CHILD FAMILY, AND MULTIPLE-CHILD FAMILY. UNDER THEORETICAL ORIENTATION, THESE DIFFERENCES WOULD IMPLY DIFFERENT OUTCOMES, FOR INSTANCE IN PATTERNS OF SOCIAL OR ATTACHMENT BEHAVIORS. THE METHOD OF SURVEYING AND OBSERVING THESE FOUR DIFFERENT ENVIRONMENTS WAS EXPLAINED. POSSIBLE DIFFERENCES AMONG THE ENVIRONMENTS THAT MIGHT ACCOUNT FOR DIFFERENCES IN INFANT SOCIAL BEHAVIORS HAVE AT LEAST TWO OVERLAPPING TRENDS. THE FIRST TREND WAS THAT OF ENVIRONMENTAL RICHNESS IN THE SIMPLE SENSE OF AVAILABILITY OF STIMULI. THE SECOND TREND WAS THAT OF TYPES OF LEARNING THAT COULD OCCUR DIFFERENTIALLY IN THE CHILD-REARING ENVIRONMENTS, DEPENDING ON THE SEQUENCE AND TIMING RELATIONSHIPS OCCURRING BETWEEN STIMULI PROVIDED AND BEHAVIORS. IT WAS EXPECTED THAT THIS ANALYSIS WOULD BE USEFUL FOR UNDERSTANDING THE PSYCHOLOGICAL PROCESSES UNDERLYING CHILD DEVELOPMENT. TABLES WERE INCLUDED.