The primary goal of a districtwide dropout-prevention program is to develop, implement, and enhance instructional and programmatic components that have proven effective in educational research and practice and thus resulted in fewer students dropping out of school prior to high school graduation. This paper describes the development and implementation of a districtwide dropout-prevention model in the Tucson (Arizona) Unified School District (TUSD), called Priority One. The district developed six program-component strands for staff development: a teachers-as-tutoring program, summer school scholarships, incentives, target allocations, and districtwide efforts. The first full year of implementation was 1993-94. The district dropout rate for grades 7-12 decreased from 8.1 percent during 1993-94 to 7.9 percent during 1994-95 to 7.35 percent during 1995-96. There was also a substantial reduction in the Native American dropout rate, which was attributed to the efforts of an advocate for Native American students. Three tables are included. (Contains eight references.) (LMI)