Early literacy promotion in pediatric primary care supports parents and caregivers reading with their children from birth, offering counseling in interactive, developmentally appropriate strategies and providing developmentally and culturally appropriate and appealing children's books. This technical report reviews the evidence that reading with young children supports language, cognitive, and social-emotional development. Promoting early literacy in pediatric primary care offers a strengths-based strategy to support families in creating positive childhood experiences, which strengthen early relational health. An increasing body of evidence, reviewed in this report, shows that clinic-based literacy promotion, provided with fidelity to an evidence-based model, has benefits for children, for parents and caregivers, and for pediatric physicians and advanced care providers as well. Reading with young children supports early brain development and the neural "reading network," and improves school readiness. High-quality literacy promotion is especially essential for children who face disparities and inequities because of social factors, systemic racism, and socioeconomic risk. All families benefit from high-quality and diverse books and from developmentally appropriate guidance supporting interactions around books and stories. Thus, literacy promotion can be a universal primary prevention strategy to strengthen families and support healthy development. Partnerships at community, local, and state levels offer opportunities for integration with other programs, services, and platforms. Literacy promotion in primary care pediatric practice, recognized by the AAP as an essential component since 2014, has become increasingly common. There are successful models for public funding at federal, state, county, and municipal levels, but sustainable funding, including payment to pediatric physicians and advanced care providers, remains a need so that the benefits of pediatric early literacy promotion and the joys of books and shared reading can truly be offered on a population level.