Teachers are often asked to implement research-based instructional programs with fidelity and to ensure that all students reach high academic standards. These requests sometimes conflict when teachers find that not all their students are benefiting from the research-backed programs. In this article, we suggest that researchers and teachers can work together to balance the importance of both program fidelity and instructional flexibility, based on findings from recent research on Peer-Assisted Learning Strategies (PALS) for Reading in Grades 2-6. We detail how teachers can learn to implement research-based practices with fidelity, as well as customize these practices to fit their own purposes. We end with general recommendations for customizing research-based practices.