Book excerpt: Networks increase interdependencies, which creates challenges for managing risks. This is especially apparent in areas such as security and enterprise risk management, where the actions of a single player in an interconnected network can wreak havoc on everyone in the network. The network, in this case, is only as strong as its weakest link. There are related problems in encouraging investments for prevention and protection, because the expected payoffs from such measures by one player are affected by the actions of other players in the network. This chapter examines the challenges of interdependent security (IDS) and strategies for addressing these, including coordination with broader networks such as industry organizations and government.