Early math skills predict later academic achievement and are of critical importance in preschool. There also are discrepancies in early math skills of preschoolers with disabilities compared with their typically developing peers. We used an experimental single-case research design, multiple probe across skills, to investigate the effectiveness of systematic modeling with mathematical language and a prompting procedure on increasing the early math skills of two preschoolers with disabilities or delays. A functional relation was observed for one participant. Equivocal findings may be due to the following: (a) challenges in assessing early math skills, which may have affected the identification of appropriate target skills, and (b) the involvement of multiple developmental domains in performing math skills, which may have affected the demonstration of target behaviors for the participant with significant fine motor and language delays.