This study evaluated the impact of a curriculum called the Early Literacy Skills Builder on the language and early literacy skills of students with significant developmental disabilities. Students in the control group received the ongoing sight word and picture instruction prescribed by their individualized education programs. Results indicate statistically significant interaction effects for the treatment group for two research team-designed measures of early literacy (the Nonverbal Literacy Assessment and a pretest/posttest for the experimental curriculum). Significant interaction effects were also found for two standardized measures (Peabody Picture Vocabulary Test III and Memory for Sentences of the Woodcock Language Proficiency Battery). Implications and future research needs are provided. (Contains 5 tables and 2 figures.)