This study investigated the extent to which a state-funded teacher professional development program designed to improve K-2 science education led to changes that persisted beyond the funding period. The study used a longitudinal, mixed-methods approach and examined persistence of changes in teachers' content knowledge, self-efficacy, instructional time, and instructional practices in science. It also examined the extent to which school contexts and resources provided ongoing support for teachers to implement what they learned in the professional development. Data sources, collected over a 5-year period, included a teacher survey, a self-efficacy assessment, content knowledge tests, interviews, and classroom observations. Findings indicated a beginning pattern of decline during the 2 years after the program ended, but outcomes remained higher than before the professional development. Contextual factors varied widely across schools and influenced, in particular, the amount of time teachers devoted to science and their decisions about instructional strategies.