Achievement and attitudes of pupils in Grades 1, 3, and 5 in the experimental school were compared with those of pupils in control schools. No systematic differences in students' achievement were found to exist between the Multiunit School and I and R Unit and their control schools. The analyses suggest two major conclusions: First, the achievement of students does not seem to be affected adversely during the transition from traditional self-contained school organization to the Multiunit plan. Second, further longitudinal data concerning the achievement of Multiunit and I and R Unit students in comparison to control school students is warranted and essential. Significant achievement gains by Multiunit students are likely to come, if at all, after the first and perhaps the second year of Multiunit operation, at a time when operational proficiency has been reached. (Author)