Individuals with significant intellectual disabilities who use augmentative and alternative communication (AAC) often fail to acquire large vocabularies. To maximize the functionality of a small vocabulary, AAC users' initial vocabulary typically consists of words that can be used frequently across contexts and functions (i.e., core vocabulary). For many AAC users, core vocabulary often references concepts rather than concrete items. For individuals with severe intellectual disabilities, however, initial AAC vocabulary often consists of concretely referenced words instead. There is little evidence that these individuals can learn to use conceptually referenced words in initial AAC. A variation of a single subject multiple baseline design across four stimuli was used to demonstrate that an individual with severe intellectual disabilities could learn to use conceptually referenced words as an initial AAC vocabulary. As a result of the intervention (a modified PECS procedure), a 9-year-old boy with multiple disabilities, including intellectual disability and deaf-blindness, learned to make appropriate use of three conceptually referenced tactile symbols for the concepts of more, done, and new as an initial communication vocabulary.