A Theory of Change (ToC) is an approach to map programmes aimed at inducing change in a specific context, with the goal of increasing their impact. We applied this approach to the specific case of handwashing and sanitation practices in low- and middle-income countries and developed a ToC as part of a systematic review exercise. Different existing sources of information were used to inform the initial draft of the ToC. In addition, stakeholder involvement occurred and peer review took place. Our stakeholders included methodological (ToC/quantitative and qualitative research) and content experts (WASH (Water, Sanitation, Hygiene)/behaviour change), as well as end-users/practitioners, policy-makers and donors. In conclusion, the development of a ToC, and the involvement of stakeholders in its development, was critical in terms of understanding the context in which the promotional programmes are being implemented. We recommend ToC developers to work with stakeholders to create a ToC relevant for practice.