This study reports on differences in children's interactional behaviors in traditional and nontraditional classrooms. The Differentiated Child Behavior Observational System which provides for systematic recording of group behavior in ongoing classroom activities, was applied in two days of observation in each of 17 classrooms (grades 1 to 3, ages 6 to 9). Two traditional (one middle-income and one low-income) and two nontraditional groups (one middle-income and one low-income) were compared. The nontraditional middle income classrooms were in private schools, the others in public schools. Significant differences were found in sheer amount of interaction, with significantly greater amounts in the two nontraditional groups. Although the general distribution of behavior among the six major categories (Gives Information; Questions; Expresses; Acts Destructively; Organizes; Represents) showed similiar patterns, important qualitative differences were shown in finer-grained analysis of the 50 sub-categories. There were significantly more higher-level cognitive statements and questions by children in the Nontraditional groups. Expressive interactions, primarily limited to routine requests and complaints in the Traditional groups, represented a greater proportion of feelings and concern for others in the Nontraditional groups. The latter also had more autonomous and creative representational interactions and far less destructive behavior. Also reported are correlations with teacher behavior, reliability of DCB and intra-group differences. (Author/MS)