Professionals who work with families during the prenatal to 5 years range (p-5) can work with colleagues across various sectors of the field to coordinate and collaborate on behalf of young children and their families. This article explores the efforts of p-5 professionals throughout Los Angeles County to strengthen their capacity to engage in cross-sector, collaborative approaches of service delivery to expectant parents, young children, and their families. A competency-based training is building capacity in the early childhood field to increase awareness of early childhood needs and promote a collaborative, cross-sector approach to positive systemic change.