This article describes the first system-wide evaluation of the Child Health Network (CHN) for the Greater Toronto Area (GTA), a partnership of 29 community and hospital care providers. The CHN performance evaluation sought to identify the impact of the network on the delivery of maternal, newborn and child health services in the GTA. CHN members identified seven criteria to be evaluated (appropriate care, accessibility, effectiveness, satisfaction, integrated and coordinated care, accountability and affordability) and then collaborated in selecting measurable indicators for each criterion. Data were compiled from administrative data sets, or collected as needed. This undertaking succeeded in providing a comprehensive assessment of the network's performance, identification of strategies to improve outcomes and network sustainability, as well as practical information that will inform the important new field of network evaluation.