Collective Impact-Strengthening the Science and Practice of Implementation Support: Evaluating the Effectiveness of Training and Technical Assistance Centers.

We introduce the second of two special issues that examine the science and practice of implementation support with takeaways for training and technical centers (TTACs). Major goals of both issues were to provide: rationale, concepts, and tools for evaluating training and technical assistance (TTA); an evidence-base for TTACs; and greater understanding of what is required to close the research-practice gap. To achieve these ambitious goals, we encouraged submissions from a broad array of individuals and groups involved in TTA. The seven articles in this second issue were written by a diverse mix of individuals affiliated with TTACs, federal agencies, research-oriented think tanks, and implementation scientists whose focus is on advancing the TTA literature. We felt that the collective wisdom garnered from their experiences would complement the first issue (June 2024) and collectively forge ahead and provide a vision of what is to come. We also thought it would be useful to provide perspectives on what it looks like when readers could examine both issues as a whole. Therefore, we included five commentaries-from the two editors and esteemed colleagues-who help provide a holistic perspective on the present and future of the science and practice of implementation support.