The stability of the financial system and the potential for systemic events to alter its function have long been critical issues for central bankers and researchers. Recent events suggest that older models of systemic shocks might no longer capture all of the possible paths of such disturbances or account for the increasing complexity of the financial system. To help assess these concerns, the Federal Reserve Bank of New York and the NRC cosponsored a conference that brought together engineers, scientists, economists, and financial market experts to promote better understanding of systemic risk in a variety of fields. The book presents an examination of tools used in ecology and engineering to study systemic collapse in those areas; a review of current trends in economic research on systemic risk, the payments system, and the market of interbank funds; and for context, descriptions of how systemic risk in the financial system affects trading activities.