Smart Predict is a mobile tablet-based dual-app system for augmentative and alternative communication (AAC) which permits vocabulary supplementation by partners to support communication by people with neurodevelopmental or neurodegenerative disease who use speech generating devices for expressive language. Partners augment word prediction capabilities while persons with complex communication needs control message construction. The purpose of this project is to evaluate Smart Predict to determine whether (1) partner engagement is increased during conversation; (2) message production is faster when the novel AAC app is used.