The evaluation of the Portland (Oregon) Public Schools' Summer Program focused on academic achievement of its students, grades K-8, who participated in 1985. Courses included arts and crafts as well as basic and remedial instruction in reading, mathematics, and language. The achievement gains of summer school students were compared to the whole district, and the achievement of various student population groups was compared. Students were categorized as remedial, enrichment, talented and gifted, or special education program participants. An increased number of lower income students were able to attend because tuition was waived for qualified students. Portland Achievement Levels Tests RIT for Spring and Fall 1985 were used to assess pre- and post-summer school levels in reading, language arts, and mathematics. Results were examined for students who were not promoted, for remedial students, and for talented and gifted students. Most groups benefitted the most in mathematics. Students who were not promoted did less well than the overall district in reading and language. Remedial students showed gains, compared to the district, especially in reading and mathematics. Talented and gifted students gained more than the district in nearly all subjects and grades. It was suggested that conclusions should be made cautiously. Several tables are included. (GDC)