This dissertation investigated patterns of child care use over time, associations between early child care participation and child outcomes in early childhood, and possible mechanisms by which child care may foster positive development, using a randomized controlled-trial evaluation of a voluntary statewide home visiting family support program for first-time young parents. Participants were 704 mothers and their children (M age = 12 months-6 years) enrolled in the evaluation study. Findings revealed three main patterns of child care use over time: (1) low early child care use; (2) organized group care plus grandparent care; and (3) organized group care only. Compared to organized group care alone, organized group care plus grandparent care was associated with higher school readiness in children as well as lower parenting stress. Parenting stress did not mediate the association between child care and children's school readiness. These findings have important program and policy implications highlighting the benefits of grandparent care in conjunction with organized group care, the importance of creating a multigenerational approach to early education, and of promoting high quality and increased access to child care for children living in challenging contexts.