Joint attention (JA), the ability to share attention to an object or event with another person, is one of the earliest identified deficits in autism spectrum disorders (ASD) and directly influences language and social development. There are several effective assessments of JA for young children (e.g., Mundy et al., 2003), but none are appropriate for school-age or adolescence. We developed a measure of response to JA and assessed individuals with ASD (n = 18) and typical development (n = 24), ages 7 to 17. Six naturalistic prompts were interleaved throughout a testing session. Discriminative validity was high: there was a broad range for both groups, though scores were lower for children with ASD. Scores in the ASD group were associated with receptive language, symptomatology, and theory of mind. Reliability across examiners was high ([kappa] = 0.875). This measure, which requires no special equipment and minimal training, was useful in capturing JA skills in older individuals with and without ASD. Further, scores were associated with theoretically related skills, indicating high external validity. Given the powerful developmental sequelae and numerous interventions for JA, this measure offers a longitudinal assessment opportunity. (Contains 4 tables.)