This study examined patterns of social interactions and play activities in Japanese day care settings. Fifty children between 6 and 36 months of age in five day care centers in Tokyo were observed over several prescribed time intervals. Variables measured during the observations included: (1) type of social interaction; (2) type of activity engaged in; (3) concentration, as determined by length of play bouts; and (4) complexity of activity. Data obtained from the observations were compared to similar data obtained in studies in the United States and the United Kingdom. Results from the observations showed that while developmental trends in social interaction and play activities were found, influences of Japanese caregivers in helping to promote a sense of group membership were also found. Few play bouts were cognitively complex. Results of the cross-cultural comparisons indicated that Japanese children engaged in more social exchanges than did children in a U.S. study, and that Japanese children showed attention spans as long as those measured in a study of British children 2 years older than the Japanese children. A reference list of 19 items is included. (BC)