Abstract It is well recognised that the involvement of different actors in health research is crucial to the success of projects and interventions, as it increases the likelihood that they will be relevant, impactful and applicable in practice. However, researchers and policy makers often lack tools for the participatory involvement of actors. One way of actively involving actors is the Theory of Change (ToC) method. A ToC is a model of a change process that describes how and why an intervention leads to the intended change or outcome in a given context. It describes the path along which change is expected to occur and provides a framework for investigating whether and how change takes place. It is a systematic methodology that can be used both prospectively and retrospectively for the planning, implementation and evaluation of interventions. The approach recognises that changes in socio-ecological systems are complex and challenging and that the causal processes are often non-linear and intertwined. A ToC workshop begins with the formulation of a clear vision for the desired change and the long-term goal of the intervention. Starting from the long-term goal, the necessary medium-term and short-term goals are then defined in a backward mapping process. Next, indicators, activities and assumptions are defined for each intermediate goal. The results of a ToC workshop can be visualised in a ToC map, which shows the causal pathways, relationships, and connections between the different components of the ToC. This visual representation helps the actors to understand the logic, connections, and assumptions underlying the ToC. This in turn facilitates a shared understanding, collaboration, and ownership among all actors involved. Overall, successful involvement of actors using the ToC method can not only enrich the research process, but ultimately also increase the health benefits of interventions and health policies.