A growing body of evidence has defined the characteristics of a quality preschool curriculum. However, less is understood about the sustainability of implementation once a preschool curriculum has been adopted. Using a qualitative methodology, we focused on factors associated with preschool teachers' continuing use of a research-based curriculum (Children's School Success; CSS) after an implementation year. Participants were 43 Head Start and prekindergarten teachers who taught children who were at risk for school failure in classrooms in five geographic sites. Of the 43 teachers, 11.6% maintained full use of the CSS curriculum in the follow-up year, 60.4% used portions of the curriculum, and the remainder had discontinued using the curriculum. Teachers in these three groups were differentiated on the basis of (a) curriculum and instructional factors (degree to which teachers liked the CSS content, believed that CSS contributed to children's learning or covered material not in other curricula, previous experience with other curriculum), (b) teachers' autonomy in choosing a curriculum, (c) resource availability, and (d) implementation history (degree to which teachers implemented CSS in the prior year). Findings highlight the complexity of the processes that determine if educational innovations will continue to be used in the preschool classroom. (Contains 5 tables.)