This study followed 18 children with developmental disabilities, whose chronological ages were between 3 years and 6 years at the start of the study, over a 2-year period. At initial observation, children communicated primarily through prelinguistic gestures, vocalizations, and single-word utterances. Children's language skills were measured every 6 months with the Sequenced Inventory of Communication Development-Revised (D. E. Hedrick, E. M. Prather, & A. R. Tobin, 1984). Prelinguistic communication rate and parental responsiveness were also measured at each observation. Development of language over time differed between participants in accordance with their entry-level communication. Hierarchical linear modeling indicated that children's level of gestural attainment, rate of communication, and parent response contingency were significant predictors of language outcome.