This study examined the effects of receiving multiple intervention services on the language, literacy, and general development of preschool children from low-income families. By employing a hierarchical linear model on a sample of 1436 children, developmental outcomes of four-year-old children receiving varying numbers of intervention services were compared: Pre-Kindergarten only (pre-K), pre-K + Early Reading First (ERF), and pre-K + ERF + Head Start. Results indicated that the additive ERF service was related to gains in alphabet knowledge. Being in classrooms with the three intervention programmes was negatively associated with receptive vocabulary knowledge and name writing skills. Participating in additional intervention programmes was not a significant predictor of any of the general developmental outcomes.