This study examined an urban school readiness initiative that developed parent leadership as a key strategy for increasing the likelihood that all children enter kindergarten ready to succeed. Parent Leaders were primarily immigrant mothers who conducted outreach activities and child developmental screenings with low income, under-served, urban and immigrant families with young children. Using a rigorous case study design, this qualitative study investigated what strategies Parent Leaders used to engage families and how their leadership influenced families, neighborhoods, and the Parent Leaders themselves. The study found that Parent Leaders (1) used highly relational strategies to engage families, (2) shifted community norms about parent leadership, and (3) developed their own identities as leaders. These findings contribute to an increased understanding of how and why parent leadership matters for school readiness research, practice, and policy, particularly in immigrant and under-served communities.