This report sets forth the design, procedures, and findings of the Ann Arbor Split-Trimester Feasibility Study. The plan is based on a school year of 216 days as opposed to the present 180 days and is organized into six split-trimester terms, with students attending five terms for a total of 180 days. The plan provides a universal 30-day summer vacation in addition to the elected split-trimester vacation term. The choice of the plan over others is justified by staff readiness, curricular flexibility, and instructional individualization. Study findings are considered under three headings: economic feasibility, instructional feasibility, and social feasibility. The report concludes that the plan is economically feasible for any school district undergoing high growth rates in pupil population. Appendixes include reports by the Instructional Feasibility Study Committee, The Class Scheduling Study Committee, and the Economic Feasibility Study Committee. Materials disseminated by the Survey Committee are also provided. (JF)