Social communication impairments are a core deficit in autism spectrum disorder. Social communication deficit is also an early indicator of autism spectrum disorder and a factor in long-term outcomes. Thus, this symptom domain represents a critical treatment target. Identifying reliable and valid outcome measures for social communication across a range of treatment approaches is essential. Autism Speaks engaged a panel of experts to evaluate the readiness of available measures of social communication for use as outcome measures in clinical trials. The panel held monthly conference calls and two face-to-face meetings over 14months. Key criteria used to evaluate measures included the relevance to the clinical target, coverage of the symptom domain, and psychometric properties (validity and reliability, as well as evidence of sensitivity to change). In all, 38 measures were evaluated and 6 measures were considered appropriate for use, with some limitations. This report discusses the relative strengths and weaknesses of existing social communication measures for use in clinical trials and identifies specific areas in need of further development.