This paper addresses the issue of assessing communication, language, and associated cognitive and behavioral abilities of minimally verbal children with autism spectrum disorder (ASD), presenting a summary of a year-long series of meetings held by a group of experts in the field of ASD and National Institutes of Health staff. In this paper, our goals were to first define the population and then present general guidelines for optimizing assessment sessions for this challenging population. We then summarize the available measures that can be used across a variety of behavioral domains that are most directly relevant to developing language skills, including oral motor skills, vocal repertoire, receptive and expressive language, imitation, intentional communication, play, social behavior, repetitive and sensory behaviors, and nonverbal cognition. We conclude with a discussion of some of the limitations in the available measures and highlight recommendations for future research in this area. Autism Res 2013, 6: 479–493. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.