What works to eradicate modern slavery? Where have evaluations of modern slavery programmes been conducted? What type of interventions have been evaluated? This paper provides an introduction to the Promising Practices Database, including an overview of the methodology used to develop it and a description of the initial findings. The Promising Practices Database collates impact and programmatic evaluations of anti-slavery and counter trafficking programming and categorizes these by terms such as country, type of modern slavery, and outcome of the evaluation.