The impact of a major curriculum revision on students' perceptions of the quality of the medical school learning environment, social supports, and their own mental and social well-being was determined. First-year students' perceptions one year before the curriculum revision were compared with first-year students' perceptions two years after the introduction of the new curriculum. In the new curriculum, students reported better overall quality of the learning environment (p = .019), a trend toward fewer stresses (p = .091), no difference in social supports (p = .721), better mental well-being (p = .043), and a trend toward better social well-being (p = .099). Students at a comparison school that did not undergo curriculum revision did not have more favorable perceptions during the study period. The findings suggest that well-considered and well-executed efforts to improve the quality of a medical school's learning environment can be successful and can raise students' perceptions of their overall well-being.