Nutrition research benefits from broad and intensive participation by stakeholders. The articles in this special issue 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 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.