The imperative for the exchange of terrorism-related intelligence information among law enforcement and security officials at all levels of government is founded on three propositions. The first is that any terrorist attack in the homeland will necessarily occur in a community within a state or tribal area, and the initial response to it will be by state, local, and tribal emergency responders and law enforcement officials. Second, the plotting and preparation for a terrorist attack within the United States will also occur within local communities. Third, information acquired for one purpose, or under one set of authorities, might provide unique insights when combined, in accordance with applicable laws, with seemingly unrelated information from other sources. This book describes the Nation-wide Sar Initiative (NSI), and the rationale for the sharing of terrorism-related Suspicious Activity Reports (SARs), and how the NSI seeks to achieve this objective.