The purpose of this study was to demonstrate the efficacy of the rhyming portion of the Promoting Awareness of Sounds in Speech (PASS) program, a comprehensive and explicit phonological awareness intervention curriculum that was designed specifically for preschool children with speech and language impairments. A single-subject research design was used to examine treatment effects among children with varying levels of communicative competence, to permit flexibility while piloting the intervention program, and to provide experimental control. The PASS rhyming module was implemented with eight children with speech and/or language impairments, following the establishment of a stable pretreatment baseline on a series of phonological awareness probes. After instruction, all of the children demonstrated substantial improvement in their rhyming ability, which generally appeared to be attributable to the intervention rather than environmental or maturational factors. These findings suggest that PASS rhyming training was an effective approach to phonological awareness instruction for the preschoolers with disabilities who comprised our sample. Thus, it appears that explicit instruction in phonological awareness skills is beneficial for children at a point earlier than is typically judged to be therapeutically appropriate.