There is great opportunity in pediatric primary care to lay the foundation for lifelong health and well-being during the critical period from infancy to early childhood. However, many of these opportunities are missed, particularly for the most vulnerable children. The challenges to equitable, universal developmental and behavioral screening in pediatric primary care must be addressed to support the health and well-being of all infants and young children. This article reviews the importance of standardized screening tools for early recognition and intervention of developmental and social-emotional needs as well as the disparities that continue to exist in screening and referral practices.