This study explored the functioning of exploratory and cautious children in open classrooms. Four areas of functioning were focused on: curiosity and exploration, learning and mastery, autonomous behavior, and interpersonal contacts. Thirty exploratory and 30 cautious children were selected through teacher ratings and exploratory tasks and observed in their classrooms throughout a school year. Observational data were collected through detailed narrative records of 5- to 15-minute periods and with a precoded observation system in which behavior was coded in predetermined categories at short time intervals. Observers had no knowledge of which children had been labeled exploratory or cautious. Results indicated primary differences in social interaction with peers, spontaneous expression of ideas and feelings and aspects of self-direction and autonomy in the classroom. However, exploratory and cautious groups were not systematically different in work persistence, management of classroom resources, the nature of contacts with teachers or the pattern of work relationships with peers. There was no simple confirmation of the hypothesis that exploratory children might be more generally effective in open classrooms than cautious children, though some patterns of behavior were different. Sex differences were discussed. (Author/SB)