Two studies were conducted on the effects of multiage classrooms. The first study investigated verbal interaction among children of different age groups and student-teacher interaction in multiage classrooms. Existing multiage classrooms in various settings were observed and information was recorded on the ages of the children initiating and receiving each interaction, the number of children in each age group who initiated interactions to the teacher, and the number of children in each age group who were present in the classroom. Interactions were classified as dominant, submissive, or neutral. Results indicate: (1) older children tended to initiate proportionately more interactions when three ages were grouped together, but not when only two ages were grouped together; (2) children of one age did not dominate the teacher's attention; (3) interaction within age groups was high and interaction between age groups was low when three age groups were present, but not when two age groups were present; and (4) no differences were found between the observed and expected number of interactions of various types initiated by children of various ages. The second study explored the effects of multiage grouping on achievement and self-concept. Children in multiage and and single age classrooms were given the Comprehensive Tests of Basic Skills for reading, math, language arts and study skills, and the Piers-Harris Children's Self-Concept Scale. There were no significant differences in the effects of sex or the interaction of classroom type and sex for the total self-concept scores or for any of the self-concept factor scores. Multiage classrooms had a higher mean score than single-age classrooms on the happiness and satisfaction factor. There were no significant differences for any of the achievement variables. (Author/SS)