The federal government has undertaken a massive reorganization in order to create the Department of Homeland Security and a parallel debate over how to organize homeland security functions has arisen at the State and Local government levels. In a time of severe budget constraints and rapidly changing threats, governments at all levels recognize the need for multiple government agencies, the private sector and non-governmental organizations to work together in order to provide effective homeland security. The effort to improve cooperation, especially at the "first responder" level, has become a major priority in the homeland security arena. How then can local governments, improve interagency cooperation for homeland security? A recent conference of government officials and homeland security experts concluded that the central coast of California has one of the best emergency preparedness systems in the country. This thesis examines the high level of interagency cooperation that has arisen among public safety agencies in Monterey County, California in order to determine what factors have contributed to their success and how they might be applied in other situations. The author proposes that theories from multiple disciplines can provide insight into the likelihood and ability of organizations to cooperate. By drawing on bureaucratic politics, epistemic community and network theories the author develops an integrated model of interagency cooperation that describes the impact of organizational structure, institutional learning and information technology on interagency cooperation.