The purpose of this project is to adapt an evidence-based practice for infants and toddlers (aged 12–24 months) at risk for ASD and their families. The proposed study builds directly on the promising results of a pilot study in which a parent-implemented program originally targeted for preschoolers called Teaching Social Communication to Children with Autism (TSC) was selected in collaboration with community stakeholders to address the needs of infants and toddlers at risk for ASD. This study will focus on specific adaptations identified during the pilot that will be needed to meet the needs of early intervention agencies, as well as infants and toddlers and their families (e.g., enhancing provider coaching and support, revising the manual to be more developmentally appropriate). The researchers will use an existing community collaborative structure to adapt TSC for use in early intervention agencies serving young children at risk for ASD. There will be three phases of the proposed research. In Phase 1, a qualitative focus group approach will be used to obtain a comprehensive understanding of how different providers and parents use, modify, and apply TSC with infants and toddlers and their families and to examine additional support that might be needed for ongoing implementation. During Phase 2, information from Phase 1 will be used to adapt TSC supports to enhance sustainability. A toddler TSC manual and accompanying supports will be developed using an iterative process of community testing and feedback. Finally, in Phase 3 of the project, the research team will conduct a community-based pilot study of the training plan and the adapted TSC program in terms of fidelity, feasibility, and promise for change in child outcomes.