Impact evaluations and implementation research produce different types of necessary information for evidence-informed action. While impact evaluations measure the attributable effects of an intervention, implementation research examines how the intervention is being implemented in different contexts, which can inform analysis of program effects and is needed to inform scale up of the intervention. The authors present three case studies in which researchers and implementers integrated implementation research and impact evaluation. They highlight what worked or what was missed and provide practical recommendations for integrating these approaches to improve evaluation evidence, which can be applied in other sectors.