Since 1987, more than 1,100 high schools in 35 states have adopted the High Schools That Work (HSTW) improvement design. The effectiveness of selected school and classroom practices included in the HSTW design was analyzed to identify implications for federal policy, the conditions that improve students' chances for success, and practices that raise student achievement. The following are among the recommendations for policymakers that emerged from the study: (1) achieve better alignment of federal and state initiatives for low-performing schools; (2) encourage tougher graduation policies; (3) encourage an academic or career focus; (4) build curriculum and instructional leadership capacity at the school level; (5) designate federal resources to support extra help and successful transition; and (6) place major emphasis on professional development as the key to school improvement. The following conditions were identified as improving chances for success: graduation and accountability policies; outside assistance; alignment of district leadership, policies, and resources; and a focus on curriculum, instruction, and student achievement. The following practices were deemed effective in raising student achievement: realizing a functional school mission; having students complete a rigorous academic core and concentration; setting high expectations; rethinking the purpose of career and technical studies; and offering high-quality structured worksite learning. (Contains 40 tables/figures.) (MN)