There is an increasing interest in the role of peers in facilitating the social interaction skills of pupils with autism spectrum disorder through peer-mediated interventions (PMI). Several reviews provide promising evidence for the effectiveness of this approach; however, there has been limited consideration of the range of outcome foci and methods used to evaluate PMI. The purpose of the current review is to provide an overview of methods used to evaluate the impact of PMI and illuminate key examples of innovative practice. Database and web searches were conducted between July and August 2015 to identify PMI studies published between 2000 and 2015. Ten studies met criteria for inclusion. The review found that although measuring the outcome of PMI at the level of target pupils has been a focus, less attention has been given to exploring the experiences of participants; the impact on peers and the extent to which PMI can truly be implemented within an educational context. Implications for future methods of evaluating PMI are discussed.