Centennial High School in Gresham, Oregon, was one of three pilot schools selected in 1983 to use a research-based school improvement process developed by the Northwest Regional Educational Laboratory. In the process, the local school establishes a leadership team to manage school improvement, collects data on student performance, uses the data to determine a high priority improvement goal, selects and implements practices that research has shown can help to meet the goal, and monitors progress toward goal achievement. Following its establishment of a leadership team and its assessment of needs based on student performance data and teachers' perceptions of problem areas, Centennial established as its two major goals a 50 percent reduction in attendance problems and 10 percent increases in achievement test scores, enrollments in advanced classes, percentages of time on task, and success rates on tests and assignments. This report describes the specific steps taken at Centennial, the use of inservice training in the program, the extent of teacher participation, the school's success in reaching the stated goals, and the school's continuing efforts at improvement. (PGD)