Considerable evidence has accumulated supporting transactional influences between early childhood behavioral inhibition (BI), parent-child and child-peer relationships, and the development of anxiety disorders in adolescence and adulthood. Drawing from this literature, the Turtle Program was designed to treat children high in BI by intervening at the level of both parents and peers. In this pilot study, we sought to determine whether benefits of participating in the Turtle Program extended to children’s classrooms in the form of increased positive social interactions with peers. Forty inhibited children (42–60 months) and their parent(s) were randomized to either the Turtle Program (n = 18) or a waitlist control group (WLC; n = 22). The Turtle Program involved 8 weeks of concurrent parent and child treatment. Trained research assistants, blind to treatment condition, coded participants’ social interactions with peers during free play at each child’s preschool at the beginning and end of treatment. Teachers unaware of group assignment also provided reports of social behaviors at these time points. Reliable change index scores revealed that both Turtle Program and WLC participants experienced relatively high rates of reliable increases in observed peer play interactions from pre- to post-treatment (73.3% and 42.1% respectively). Additionally, Turtle Program participants experienced high rates of reliable increase in observed initiations to peers (73.3%) as well as a moderate degree of reliable decrease in teacher-reported displays of fear/anxiety (33.3%). These data provide preliminary, but promising, evidence that increases in children’s social behaviors as a result of participation in the Turtle Program generalize to their preschool classrooms.