"This document provides a synthesis of guidance specifically aimed at Theory of Change (ToC) processes in a Global Environment Facility (GEF) context, as part of a growing suite of Scientific and Technical Advisory Panel (STAP) documents that support the design of interventions in meeting the GEF’s goal to apply leading practices to deliver transformational change. ToC interacts with many other elements of project and program design. In this primer, these interactions are only discussed briefly in terms of their implications for ToC and cross-references to other STAP, GEF or external sources are often provided for more detail." (Foreword)