Physical therapists (PTs) are often one of the first professionals to evaluate children at risk. To examine the effect of an early screening training on pediatric PTs’: (1) knowledge of autism spectrum disorder (ASD), (2) clinical self-efficacy, and (3) identification of markers. Twenty-six PTs participated in a 2-day “Early ASD Screening” workshop. The ASD Knowledge and Self-Efficacy Questionnaire, and video case study analysis were completed pre- and post-training. Changes following training were significant for ASD knowledge related to etiology and learning performance, early signs, risk factors, and clinical self-efficacy. Rating the videoed case study after the training, was significantly more accurate than it was before. Training PTs is important for enhancing early identification of ASD.