The Office of Research and Evaluation of the Dearborn Public Schools (Michigan) presents a longitudinal study to analyze grade nine student academic growth over a 2-year period utilizing the results of the Tests of Achievement and Proficiency (TAP). The TAP is a nationally normed test designed to assess student progress toward widely accepted secondary school goals in the basic skills and basic curriculum areas. The TAP, rather than being content specific, emphasizes student skills and the ability to use information. The TAP was administered to grade 9 and grade 11 students during May in 1978 through 1981. During both October 1979, and October 1980, staff in-service sessions were conducted which emphasized making effective use of the TAP test data. It was determined that a study of same students from grades 9 to 11 would help determine the effectiveness of the high school curriculum. Discussed are: (1) 4-year achievement trends, (2) analyses of variance of achievement gains by high school, (3) the city grade 9 to 11 achievement trend, (4) the student population, (5) comparison of achievement of students who left school and new students, (6) 2-year gains by tests by achievement level, and (7) interpretation and instructional use of TAP longitudinal achievement data. (PN)