Promoting positive relationships with peers is an important support for children who exhibit social withdrawal. Children who show extreme shyness or are identified as self-isolating are at risk for developing internalizing conditions, which can also lead to poor social and academic outcomes. These children may benefit from targeted support to develop relationships with peers. Identifying effective social interventions that support children who exhibit internalizing behaviors such as social withdrawal in preschool classrooms is a critical need. A nonconcurrent multiple baseline across three focal U.S. children design was used to test the effects of an adapted version of Stay, Play, Talk (SPT) that included peer choice on the estimated duration of social play for young children who were socially withdrawn. A functional relation was found between the implementation of SPT with peer choice and focal children's social play. This study demonstrates that SPT with peer choice may be an effective and socially valid intervention for increasing the social play of preschoolers who are socially withdrawn in classrooms. More research is needed to better understand to what extent this adapted SPT intervention impacts children's social networks, broader social-emotional development, and specific internalizing behaviors when implemented over a longer period.