Utilizing the regression-discontinuity research design, this article explores the effectiveness of a developmental English program in a large, multicampus community college. Routinely collected data were extracted from existing records of a cohort of first-time college students followed for approximately 6 years (N = 1,473). Results are consistent with a conclusion that students' participation in the program increases English academic achievement to levels similar to those of students not needing developmental coursework. The findings are also consistent with a conclusion that those students in greatest need of developmental English benefit the most from the program. This study provides an inexpensive, inferentially rigorous, program evaluation strategy that can be applied with few additional efforts to assess existing programs and to guide policy decisions. (Contains 2 tables, 2 figures and 3 notes.)