The purpose of this study was to explain the variability in data collected from a single-case design study and to identify predictors of communicative outcomes for children with developmental delays or disabilities (n = 4). Using SAS® University Edition, we fit multilevel models with time nested within children. Children's level of baseline communication and teachers' frequency of strategy use when directed at the children predicted their outcomes. These results indicate that children's initial level of communication predicted their communicative outcomes and also that positive associations exist between teachers' implementation of evidence-based communication strategies when they are directed toward children with disabilities and the children's communicative outcomes. Implications for research and practice are provided. [This article was published in "Developmental Neurorehabilitation," v19 n3 p197-202 2016.]