Published results of efficacy and effectiveness studies on complementary health approaches should lead to widespread uptake of evidence-based practices, but too often, the scientific pathway ends prematurely, before the best ways to improve adoption, implementation, and sustainability can be determined. The National Center for Complementary and Integrative Health (NCCIH) supports the full continuum of the biomedical research pipeline, whereby a complementary health intervention moves from basic and mechanistic research through efficacy trials and through dissemination and implementation. Implementation science has traditionally been thought of as something that only happens after efficacy and effectiveness have been demonstrated, but it can be prudent to evaluate implementation measures earlier in the process. Implementation science assesses more than just barriers and facilitators; it evaluates specific implementation strategies and characterizes the extent that the intervention is modified within the context of the implementation strategy and health care delivery setting. The best choices for implementation science in complementary health interventions depend on the research questions. Implementation science that tests strategies to address implementation at multiple ecologic levels is a high priority to NCCIH.