Despite the variety of positive influences siblings have on developmental outcomes, very few interventions targeting these outcomes include siblings. In this article, we argue that practitioners should consider including siblings in interventions. We provide evidence highlighting the positive influence siblings have on three developmental outcomes: prosocial behavior, communication, and literacy. Additionally, we explain the potential benefits of including siblings in interventions targeting these three outcomes, provide recommendations and examples regarding how to include siblings in these interventions, and present cautions to including siblings in interventions. Lastly, we include questions to guide practitioners as they consider including siblings in interventions. Based on the information presented in the article, we conclude that one way for practitioners to enhance interventions is to include siblings.