Homeless pregnant women have complex health and social service needs that require services from many different agencies in a short period of time. Toronto Public Health’s Homeless At-Risk Prenatal (HARP) team provides intensive prenatal case management to high-risk homeless pregnant women in Toronto, focusing on service coordination as a primary intervention. In-depth interviews were conducted with service providers who work with homeless pregnant women in Toronto to answer the question: what aspects of service coordination are most effective for homeless pregnant women? The most critical aspects of effective service coordination are the informal relationships between providers working across the service community. Ten activities that enhance service coordination are described in detail and a conceptual framework for integrating the findings of this study into practice is provided.