Outcome harvesting is a qualitative approach to ex post evaluation of social change results. Rather than testing for a specific impact of the intervention at hand, it consists in, in collaboration with stakeholders: broadly making sense and collecting evidence on outcomes, investigating how these were produced and whether and how the intervention may have played a role in this process, before substantiating these outcomes with external sources. Outcome harvesting is a utilisationfocused approach: it aims at producing knowledge for action. It is particularly useful in the case of complex interventions; when the effects of an intervention are previously not known or identified; or when the intervention has been significantly modified since its inception.