This study replicated and extended the evaluation of a stimulus-stimulus pairing procedure reported in two recent studies in which researchers have suggested that vocalizations can become conditioned reinforcers for their own emission as a result of stimulus-stimulus pairing. A multiple baseline design across phonemes evaluated effects of a stimulus–stimulus pairing procedure on frequency of phonemes uttered by a child with autism. Data were collected during pre-session, post-session, and follow-up periods across three conditions: baseline, control, and stimulus-stimulus pairing. During baseline, frequency of targeted phonemes was recorded absent any experimenter interaction and prior to introduction of the pairing procedure. During the control condition, the experimenter vocalized the target phoneme and, after a 20-s delay, presented a preferred stimulus to the child. Preferred stimuli were identified via stimulus preference assessment. During pairings, the same phoneme was paired with delivery of preferred items by eliminating the 20-s delay between the experimenter’s utterance and delivery of the preferred stimulus. Results from post-session observations during the pairing condition showed little or no increase in target sounds. Data from the follow-up sessions, occurring 30-m after the post-session observations, showed occasional but inconsistent increases. Practical and theoretical implications of the results will be discussed.