This document provides a toolkit for European Structural and Investment Funds (ESIF) programme managers to support social innovation. It begins with an overview of how social innovation is addressed in EU policies and defines key concepts. It then covers theories relevant to social innovation such as capabilities approach, service innovation, transition theory and changemaker theory. It provides guidance on developing an innovation strategy for ESIF programmes and supporting the innovation process and capacities required at project level. It includes practical tools, cases and an implementation plan to help ESIF managers operationalize social innovation.