We examined the effectiveness of systematic prompting of peer-related behaviors delivered during small group academic instructional sessions with three dyads of preschool-aged children with deficits in social competence. One child was randomly assigned as the target child in each dyad. A multiple-probe single-case research design was utilized to examine the functional relation between a system-of-least prompts procedure and the frequency of unprompted peer-related social behaviors emitted by target children during small group instructional sessions. The results support a functional relation between systematic prompting and peer-related behaviors, and all three target children increased their use of peer-related behaviors. Furthermore, we examined the effect of intervention on the untrained peer play partner (i.e., observational learning). Two of the three peers increased their use of peer-related social behaviors; however, results were variable and did not support a functional relation. Our study extends the research in this area by examining the effectiveness of small group instruction on potentially context dependent, complex social behaviors (e.g., sharing materials, complimenting a friend, offering to help). (author abstract)