In a chapter in The Oxford Handbook of Program Design and Implentation Evaluation, Nova Scholar Rebecca Etz and colleagues discuss their randomized trial of a low-cost approach to supporting diabetes registries in primary care settings, the Supporting Practices to Adopt Registry-Based Care (SPARC) study. While, when compared to control conditions, the approach supported registry implementation, success was not consistent across intervention practices. The authors used contructs from the Consolidated Framework for Implementation Research to help identify successful and unsuccessful implementers and barriers and facilitators to successful implementation.