To assess the reliability and construct validity of the Penetration-Aspiration Scale in children.This was a retrospective cohort study of pre- and postoperative video modified barium swallow studies from children who underwent interarytenoid injection augmentation for unexplained persistent pharyngeal dysphagia. Two pediatric speech and language pathologists reviewed each study twice in a blinded and randomized fashion.Tertiary academic pediatric hospital.Thirty children were identified with adequate pre- and postoperative modified barium swallow studies within 4 weeks of intervention. Children were separated into clinical outcome groups based on ability to advance to thinner diet consistencies postoperatively. Construct validity was assessed with a mixed linear model to test the hypothesis that only the clinically improved group would receive better Penetration-Aspiration Scale scores after surgery. Reliability was assessed by calculating chance-corrected agreement between raters (interrater) and raters' repeat evaluations (intrarater).Inter- and intrarater reliabilities (Cohen's κ) were both excellent. Results of the mixed model revealed a significant interaction between outcome group and pre- and postoperative time interval. As hypothesized, this involved a significant improvement in Penetration-Aspiration Scale score only in the improved group.These findings suggest that the Penetration-Aspiration Scale is a reliable and valid measure of clinical response to interarytenoid injection augmentation in children.