Promoting positive relationships among young children is an important step towards improving their long-term social and academic outcomes. Children who have low rates of interactions with peers, who are identified as self-isolating, and who demonstrate other internalizing behaviors are at-risk for poor social and academic outcomes and therefore, are likely to need targeted support to develop relationships with peers. Identifying these social interventions that support children who have internalizing behaviors in preschool classrooms is a critical need. A non-concurrent multiple baseline across three target children design was used to test the effects of an adapted version of Stay, Play, Talk that included peer choice on the estimated duration of social play for young children who have internalizing behaviors. A functional relation was found between the implementation of SPT with peer choice and target 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may be an effective and socially valid intervention for increasing the social play of preschoolers who are socially withdrawn in the classroom. 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 of time. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]