The positive relationship noted between greater knowledge of PEERS concepts and improvements in overall rapport demonstrates that adolescents at post-treatment have a better understanding of social skills and an improved ability to implement them more appropriately in vivo. This finding suggests PEERS not only targets knowledge base but also improves social skill implementation and performance. The other CASS ratings, such as positive affect (i.e., smiling, nodding, etc.), are not overtly addressed or taught in PEERS, but ideally result after gaining a foundation in appropriate conversation skills and experiencing success while utilizing these skills in vivo with peers and potential friends. Since all of the CASS items do not directly match with specific skills taught in PEERS, this could account for the lack of significant improvements across all domains observed in vivo even though the adolescents in PEERS demonstrated an increase in social skill knowledge. Further, it may take adolescents less time to learn concepts taught in PEERS, while it takes longer to develop and implement these skills in vivo. Nonetheless, it is encouraging that adolescents completing PEERS demonstrated a significant improvement in vocal expressiveness and a trend toward improved overall quality of rapport following treatment.