Purpose: This study reports a secondary analysis of the nature of communicative functions and modalities used in initiations and responses of minimally verbal preschoolers with severe autism spectrum disorder (ASD) from a previously published study (Thiemann-Bourque, Feldmiller, Hoffman, & Johner, 2018). This analysis focused on the final cohort (n = 6) from a group design study (N = 45) that examined a peer mediation and speech-generating device (SGD) intervention compared to an SGD-only condition. Method: After teaching peers to use an iPad as an SGD within a modified stay-play-talk approach, school staff implemented SGD instruction in child-peer dyads during typical preschool activities. To investigate individual differences among children who demonstrated increased communication acts in the peer + SGD condition, changes in reciprocity, modalities used, and communicative functions were examined using a multiple-baseline design across children. Fidelity of implementation and social validity data were also collected. Results: Six children with ASD and their peers demonstrated more balanced reciprocity, with individual differences in how and why children communicated during exchanges. That is, all children with ASD increased in SGD use as their primary communication mode; 3 children used different modalities including more speech, and 3 children used primarily gestures and SGD. The most frequent function expressed was requests for objects. More modest increases were observed in comments and requests for actions, with negligible changes in gaining attention. Social validity reports by naïve judges reflected clear improvements in communication interactions. Conclusion: Findings are promising for a preschool SGD intervention that can expand children's modalities and communicative functions to engage in balanced exchanges with peer partners.