Black and white students attending integrated, non-integrated, and magnet schools in Saint Louis, Missouri, were subjected to the California Achievement Tests in 1980-81, the first year of a system-wide mandatory desegregation plan in the district. Results are presented in this report in the form of statistical tables and textual analyses. Findings indicate that: (1) in both integrated and magnet schools, white students had higher posttest averages than black students, although overall pretest to posttest gains were similar; (2) blacks in non-integrated elementary and middle schools had slightly higher gains than blacks in integrated elementary and middle schools; (3) gain scores of blacks in non-integrated and in integrated secondary schools were similar; (4) blacks in magnet schools had higher pretest and posttest scores than blacks in non-integrated and integrated schools, but mean gains of magnet and non-magnet students were similar; and (5) whites in magnet schools had higher test averages than whites in integrated schools, but gain scores were about the same. It is suggested that the first year of desegregation in Saint Louis public schools seems to have had no differential effects on students' achievement, although the results cannot be considered conclusive. (Author/MJL)