To raise vocational completers' academic achievement through school reform, the High Schools That Work (HSTW) network of the Southern Regional Education Board (SREB) promotes 10 key practices for raising academic achievement. The impact of these key practices was examined in a study of how 424 schools adopted them in the following six clusters: curriculum standards; instructional goals; academic/vocational integration; guidance counseling; teacher practices; and work-based learning. The study used data from multiple sources, including teacher and student surveys, high school transcripts, and achievement test scores. Overall, increases in the proportion of students meeting the HSTW curriculum standards had a large impact on achievement gains in science, reading, and mathematics. Changes in the proportion of students perceiving that their academic and vocational teachers were working together to improve students' academic skills had almost as much positive effect as curriculum changes did. Increases in the amount of time students spent talking to their guidance counselors and teachers about their school program were directly associated with increases in the schools' mean assessment scores. The other clusters seemed to have little or no explanatory power for predicting school changes in academic achievement. (Twenty-two tables/figures are included. Appended are the 10 HSTW key practices.) (MN)