The Mobile Autism Risk Assessment (MARA) is a new, electronically administered, 7-question autism spectrum disorder (ASD) screen to triage those at highest risk for ASD. Children 16 months-17 years (N = 222) were screened during their first visit in a developmental-behavioral pediatric clinic. MARA scores were compared to diagnosis from the clinical encounter. Participant median age was 5.8 years, 76.1% were male, and most participants had an intelligence/developmental quotient score >85; 69 of the participants (31%) received a clinical diagnosis of ASD. The sensitivity of the MARA in detecting ASD was 89.9% [95% CI = 82.7-97]; the specificity was 79.7% [95% CI = 73.4-86.1]. In a high-risk clinical setting, the MARA shows promise as a screen to distinguish ASD from other developmental/behavioral disorders.