Early Reading First (ERF) was created to address problems related to language and development among economically disadvantaged and language-minority preschool children through quality classroom processes, professional development, and instruction. More than any previous initiative, ERF specifies what early literacy instruction should look like in preschool classrooms; however, to date, scant research has examined the effectiveness of the program. In this quasi-experimental study, the effectiveness of ERF preschool enrichment was evaluated through comparison with the performance of demographically similar children from the same school district who received practice-as-usual instruction. As in previous research, ERF-enriched instruction was found to enhance acquisition of alphabet knowledge and print concepts. Unlike previous studies, however, it was also found to promote vocabulary development. Multilevel models were chosen to take into account the non-independence of students in the same classroom in testing the effects of ERF.