The military is currently attempting to develop itself into a force capable of networkcentric operations. While this effort has highlighted the military's dependence on interacting networks, it has also shown that there is a huge gap between what we need to know about networks and our fundamental knowledge about network behavior. This gap makes the military vision of NCO problematic. To help address this problem, the Army asked the NRC to find out whether identifying and funding a new field of "network science" could help close this gap. This report presents an examination of networks andthe military, an analysis of the promise, content, and challenges of network science, and an assessment of approaches to creating value from network science.