This systematic review of research on early childhood programs seeks to identify effective approaches capable of improving literacy and language outcomes for preschoolers. It applies consistent standards to determine the strength of evidence supporting a variety of approaches, which fell into two main categories: comprehensive approaches, which include phonemic awareness, phonics, and other skills along with child-initiated activities, and developmental-constructivist approaches that focus on child-initiated activities with little direct teaching of early literacy skills. Inclusion criteria included use of randomized or matched control groups, evidence of initial equality, a minimum study duration of 12 weeks, and valid measures of literacy and language. Thirty-two studies evaluating 22 programs found that comprehensive early childhood programs that have a balance of skill focused and child-initiated activities programs had significant evidence of positive literacy and language outcomes at the end of preschool and on kindergarten follow-up measures. Effects were smaller and not statistically significant for developmental-constructivist programs. (author abstract)