PROJECT SUMMARY Augmentative and Alternative Communication (AAC) intervention can increase language, literacy, social, and adaptive skills for children with severe communication impairments. However, AAC is underutilized in speech- language therapy for toddlers with intellectual and developmental disabilities (IDD). Hybrid telehealth models can transform the delivery of early AAC interventions by expanding access to speech-language pathologists (SLPs) with AAC expertise and reducing geographic and transportation barriers in underserved communities. The purpose of this proposal is to develop and pilot test a hybrid telehealth AAC intervention for toddlers with IDD and their families. We employ an implementation science approach, using systematic qualitative methods to identify caregiver and SLP preferences and single-case experimental design methods to assess the feasibility of the AAC intervention. The central hypothesis is that the intervention will improve caregivers’ use of AAC strategies, which will lead to increases in children’s expressive communication skills. Three specific aims are proposed. Aim 1: Determine stakeholders’ preferences and needs for two key AAC intervention components: (a) service delivery and (b) strategies to enhance treatment adherence. We will conduct interviews with caregivers and SLPs to assess their needs and preferences regarding the intervention. Interview findings will inform initial modifications to the service delivery model and treatment adherence strategies investigated in Aims 2 and 3. Aim 2: Develop an AAC intervention through iterative testing cycles. We will conduct six multiple baseline designs across behaviors to refine the AAC intervention and demonstrate preliminary efficacy using an in-person service delivery. Findings from this study will inform adaptations for a hybrid telehealth delivery of the AAC intervention, involving both in-person and telehealth sessions evaluated in Aim 3. Aim 3: Conduct a pilot test of a hybrid telehealth AAC intervention. We will pilot test the hybrid telehealth AAC intervention using a combination multiple-probe design across participants and behaviors. Nine parent-child dyads will receive 24 intervention sessions, eight sessions provided to families in-person, and 16 provided via telehealth. The primary outcome is caregivers’ use of AAC intervention strategies, and the secondary outcome is child communication acts. This proposal is innovative because it uses implementation science methods to develop a novel hybrid telehealth AAC intervention that is feasible, acceptable, and appropriate for its end-users, increasing the likelihood of widescale adoption in routine clinical practice. The project is significant because it addresses a critical need for early AAC language interventions designed for home use. Our expected outcomes are to have developed the AAC intervention and implementation strategies in preparation for an R01 application to conduct a large-scale clinical tr...