We evaluated the role of digitized speech output on the maintenance of requesting and frequency of vocalizations in three children (ages 3, 4 and 13 years old) with developmental disabilities. The children were taught to request access to preferred objects using an augmentative communication speech-generating device (SGD). Following acquisition, rates of requesting and vocalizations were compared across two conditions (speech output on versus speech output off) that were alternated on a session-by-session basis. There were no major or consistent differences across the two conditions for the three children, suggesting that access to preferred objects was the critical variable maintaining use of the SGDs. The results also suggest that feedback in the form of digitized speech from the SGD did not inhibit vocalizations. One child began to speak single words during the latter part of the study, suggesting that in some cases AAC intervention involving SGDs may facilitate speech.