This document provides guidance on evaluating the impact of research projects, particularly those funded by the Global Challenges Research Fund (GCRF). It discusses defining impact goals, selecting evaluation designs, determining the reach of impacts, and communicating evaluation findings as evidence of impact. Key evaluation concepts covered include theories of change, formative and summative evaluation, attribution versus contribution, and qualitative and quantitative methods. The document also provides templates and examples to help researchers plan for impact evaluation from the start of a project.