The purpose of this study is to provide content validity evidence for the Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP). A national panel of 13 experts provided an evaluation of the domain relevance, age appropriateness, method of measurement appropriateness, and domain representation across the three levels of the Milestones Assessment, Early Echoic Skills Assessment (EESA), and Barriers Assessment. Overall, the content validity evidence for the VB-MAPP Milestones, EESA, and Barriers Assessment was moderate to strong across the evaluated areas although there were areas with limited or conflicting support. The evidence suggests that the scores of the VB-MAPP provide information relevant to the target behaviors of interest but a few domains may not be fully represented by their specific items.