Pediatricians and family practitioners increasingly provide free picture books and anticipatory guidance about reading aloud as part of routine health supervision for infants and young children, and arrange for volunteers to read aloud to children in the waiting rooms. These interventions comprise the Reach Out and Read (ROR) model, which has been adopted by more than 2000 clinical sites nationally. To date, 12 published studies have evaluated ROR and its variations, including three prospective, controlled trials. All but one have shown associations between ROR and increased reading aloud; additionally, four studies have linked program exposure to clinically meaningful increases in child language. Nonetheless, conclusive evidence of efficacy is lacking. This article provides a systematic, critical review of the literature, focusing on theoretical assumptions, issues of study design and measurement, and directions for future research.