As more mothers with young children enter the workplace, there is an increased need for non-maternal child care services. Prior research indicates that the type of child care utilized for children under age six not only affects maternal labor force participation, but is a critical factor in later developmental outcomes for children. Within this context, understanding how working mothers choose child care for their young children is important. A growing body of research has examined influences on mothers’ child care choice behaviors. Based on Bronfenbrenner’s ecological systems theory, this article proposes a theoretical model that examines maternal child care selection under the influence of a range of environmental context variables (including neighborhood and state policy factors), family characteristics, and child factors. This article organizes and reviews the related literature within the context of the proposed model. The purpose is to provide an empirical knowledge base that can inform the development of quality child care services and policies. The article then concludes with suggestions for social welfare policy and practice on how to improve access to high quality child care for working mothers. (Author abstract)