The rising prominence of more rigorous approaches to measuring conservation outcomes has included greater adoption of impact evaluation by conservation non-governmental organizations (CNGOs). Within the scientific literature, however, little consideration has been given to the unique and specific roles of CNGOs in advancing impact evaluation. We explore these issues in the context of one CNGO—Conservation International (CI)—and its experiences producing, using and funding impact evaluations over the past decade. We examine the contributions of impact evaluation to CI's mission at three different stages of CI's strategy: innovation, demonstration and amplification. Furthermore, we review incentives and barriers encountered by CI in its 10+ years' experience in impact evaluation. More coordinated and strategic use of impact evaluation by CNGOs would facilitate learning and promote accountability across the conservation community.