The purpose of this study is to examine dosage effects of early intervention programs on preschool children's language, literacy, and general development. Children will be assigned to one of three groups: (1) pre-kindergarten only, (2) pre-kindergarten and Early Reading First, or (3) pre-kindergarten, Head Start, and Early Reading First. Specifically the project seeks to determine: (1) whether children receiving multiple intervention services demonstrate greater gains in language and literacy outcomes than children participating in fewer programs, (2) whether children receiving multiple intervention services demonstrate greater gains in global developmental outcomes, and (3) how characteristics and quality of early intervention play a role in producing benefits. Results are expected to disentangle how multiple programs play a role in children's development and inform development of intervention services that could ultimately support individual children's language, literacy, and general development. The study will also inform policymakers and program administrators regarding the appropriate level of dosage required for effective intervention efforts.