Participatory system dynamics modeling: advancing equity through contextualized implementation science in global health.

Implementation science is central to advancing health equity in low- and middle-income countries (LMICs), yet many interventions continue to fall short of sustained impact. These failures are not merely technical or logistical; rather, they stem from a deeper epistemic gap: the inability of dominant implementation approaches to account meaningfully for contextual complexity. By treating "context" as a static backdrop or checklist of barriers and facilitators, existing approaches overlook how dynamic interactions, institutional logics, and local power relations shape implementation outcomes over time. We argue that Participatory System Dynamics Modeling (PSD) offers a transformative shift. Unlike conventional methods, PSD integrates diverse sources of evidence, including administrative data, prior research, expert insight, and lived experiences, into a logically consistent, interactive simulation model. PSD invites stakeholders to co-create these models, surfacing feedback loops, time delays, trade-offs, and unintended consequences that traditional frameworks often miss. We outline how PSD enables researchers and practitioners to move beyond linear planning and surface-level stakeholder consultation by co-creating dynamic models that reflect local complexity, power dynamics, and feedback loops. Drawing from examples across LMICs, we illustrate how PSD strengthens implementation by aligning with local realities and enabling systemic reflection. We recommend embedding PSD into health planning, research, and training infrastructures as a capacity-building pathway to advance its methodological uptake in implementation science and strengthen the global capacity to deliver health interventions that are context-responsive, system-informed, and grounded in LMIC realities.