Nutrition research benefits from broad and intensive participation by stakeholders. The articles in this series demonstrate that understanding participation is complex because it incorporates the dimensions of stakeholders, activity, time, and intensity. Early involvement in research can help prioritize the problems to be addressed, refine the specific research question, and determine acceptable community-based approaches to be used in an intervention. The included studies examined the construct of participation and the diverse means by which it can be measured. They demonstrated how knowledge gained from early participation influenced the direction of interventions and increased relevancy for the community. The researchers assessed participation intensity during the intervention phase to help explain project outcomes and provide estimates of the magnitude of the effect that could be achieved if high-level participation of stakeholders was universal. In addition, participation in the analysis process was a key component of some of the articles in this series, demonstrating the richness of understanding that can be obtained through collaborative analyses. The included papers provide insight into how to define and measure participation, how to explore approaches to encourage participation of direct and indirect beneficiaries, and how participation at different time points and by different stakeholders can validate and support interventions and enhance effectiveness. As such, the series serves as a valuable reference to researchers, program and policy designers, implementers, and evaluators to increase the benefits of community-based interventions for nutrition outcomes.