We investigated the clinical validity of the BADEC, an abbreviated, five-item version of the Autism Detection in Early Childhood, level-2 screening tool for autism. Initially developed by Nah et al. (2019) using a research sample, the present study replicated Nah et al. (2019) procedures in a clinical population. Using a cutoff score of five, five items were identified as most effective in discriminating children who later received an ASD diagnosis by an interdisciplinary team. This algorithm had improved validity compared to the original research algorithm. Results supported the efficacy of a very brief, easy to administer ASD screening tool in identifying children under three who are likely to have ASD.