that require only one-word answers, particularly yes/no questions (Light, Binger, & Kelford Smith, 1994). Thus, both the lack of opportunities to communicate and the types of opportunities that are provided may contribute to low rates of multi-symbol message production. Fourth, aided AAC systems may, in and of them- selves, impact expressive communication in unique ways. For example, even preschoolers and kinder- garteners without disabilities who use aided AAC systems in research studies tend to rely on single symbol messages (Smith, 1996; Sutton & Morford, 1998). Whether this phenomenon can be fully