The current study investigated the utility of the Brief Observation of Social Communication Change-Phrase Speech Young Fluent (BOSCC-PSYF) as an outcome measure of treatment response by analyzing the measure's psychometric properties and initial validity. The BOSCC coding scheme was applied to 345 administrations from 160 participants diagnosed with autism. Participants included individuals of any age with phrase speech, or individuals under the age of 8 years with complex sentences. All were receiving behavioral intervention throughout the study. Test-retest and inter-rater reliability were good for the Early Communication and Social Reciprocity/Language domains, and fair for the Restricted and Repetitive Behavior domain. Significant changes occurred over time in the Early Communication and Social Reciprocity/Language domains, and Core Total scores. The BOSCC-PSYF may provide a low-cost, flexible, and user-friendly outcome measure that reliably measures changes in broad social communicative behaviors in a short period of time.