This study investigates cooperation in conversation among group members at five educational levels. In groups of six (three males and three females) second-, fifth-, ninth-, and twelfth-graders and college students met for 10 meetings of 20 minutes to an hour's duration. Members decided discussion topics and procedures. These meetings were tape recorded and the eighth meeting was transcribed as the source of data for each group. Each remark of a transcript was coded independently by two coders into one of five categories which served to describe how a remark was related to directly preceeding remarks on a particular topic. These categories were: unrelated; tangential; related; factual evaluation/elaboration/question; and perspective-oriented evaluation/elaboration/question. Developmental changes in conversational quality were assessed primarily by developmental trends in the proportion of remarks in each of the five categories of topic relatedness. Unrelated and tangential remarks were frequent only among second graders. Frequency of related remarks was high among elementary school students and lower among high school students. More complex remarks were frequent among ninth graders and increased in frequency among older students. Perspective-oriented statements were noticeably frequent only among twelfth graders and college students. Results are taken as evidence that the conversational quality achieved within small groups changes markedly across the public school age span. (Author/RH)