Acosta J, et al. - Because sleep problems are common and associated with externalizing behavior problems in young children, especially among young children with developmental delay (DD), researchers ascertained if parent-child interaction therapy (PCIT) resulted in decreases in child sleep problems and whether initial sleep problems moderated the effect of PCIT on child behavior. Participants in the study were 44 children with DD or borderline DD and co-occurring clinically significant externalizing behavioral problems and their mothers. The data presented in this work showed a significant direct effect of PCIT on sleep problems decreases. In addition, moderation analyses showed that lower levels of child sleep problems during pretreatment were related to higher improvements in child compliance vs higher levels of child sleep problems during pretreatment.