External challenges for individuals who need or use AAC who are learning language: lived experiences, key research findings, and future directions.

Language skills are essential to effective communication, but learning language is by no means a simple process for individuals with developmental disabilities who cannot rely on speech alone to be heard and understood. Research demonstrates that augmentative and alternative communication (AAC) interventions positively impact development across language domains (e.g., pragmatics, semantics, morphosyntax) and may also benefit speech production. However, these gains can only be realized if people have timely access to effective AAC and have meaningful opportunities to interact with others. This paper integrates the lived experiences of individuals who need or use AAC and their families with key research findings to highlight external challenges that may negatively impact language learning, including delays in access to AAC, service providers' limited competencies in AAC, the lack of fit between AAC systems and user needs and strengths, limited opportunities for social interaction, and communication partners with limited experience and training in AAC. Future research, technology development, and policy change are urgently required to reduce these barriers. People who need or use AAC and their families must be involved as equitable partners in this work to ensure that it addresses their most pressing needs and results in meaningful and valued outcomes.