The Detroit Public Schools High School Improvement Project (HSIP), a four-year program beginning with the 1981-82 school year, improved levels of student achievement in basic reading, writing, and mathematics skills at participating schools. Improvements were also a little greater than those at comparable non-participating schools. This final evaluation report on HSIP is presented in four parts: (1) a summary of evaluation findings concerning basic skill achievements, attendance, school climate, and process evaluation; (2) a detailed product evaluation, including evidence on basic skill achievements and attendance at project schools; (3) a school climate evaluation report for each of the participating schools; and (4) individual school process evaluation reports for the eight HSIP schools. The ultimate purpose of the process evaluations was to learn more about what makes for an effective local school. To that end, evaluations focused on the following questions: (1) what worked well? (2) what impeded progress? and (3) how could the process have been improved? The answers to those questions are included in the report. (PS)