This evaluation of the Portland Public Schools Summer School 1984 Program analyzes achievement gains on the Portland Achievement Levels Tests for three student groups: (1) regular education; (2) not promoted; and (3) talented and gifted (TAG). The four-week program served 743 students, primarily from grades one to eight. Eleven subject areas were offered ranging from non-academic subjects to remedial, or enrichment, instruction in reading, mathematics, and language. Portland Achievement Levels RIT scores for spring and fall of 1984 were used to assess pre- and post-summer school achievement levels in reading, mathematics, and language. Mean RIT scores and gains for grades 3 through 7 are presented for each summer school program group and for the district. Spring and fall scores for 1983 for students in the 1984 summer school program and the district are also included. Achievement results for 1984 for each group are compared to district and 1983 results. In 11 of the 15 grade/subject comparisons, the not promoted group achieved summer achievement gains greater than the district average. There is some evidence that these gains are attributable to their summer instruction. Promoted students with average, or above average, achievement showed no consistent pattern of gains or losses relative to the district. (BS)