The United States is one of the world's largest producers, consumers, exporters, and importers of agricultural commodities. However, some of these imported products may contain exotic pests and diseases. According to the Department of Homeland Security (DHS), invasive species cause an estimated $136 billion in lost agricultural revenue annually. The terrorist attacks of September 11, 2001, heightened concerns about agriculture's vulnerability to terrorism, including the deliberate introduction of livestock, poultry, and crop diseases. Under the Agricultural Quarantine Inspection (AQI) program, international passengers and cargo at U.S. ports of entry are inspected to seize prohibited material and intercept foreign agricultural pests. Historically, the USDA was responsible for the AQI program, but the Homeland Security Act of 2002 split responsibility for the AQI program between DHS and the USDA's Animal and Plant Health Inspection Services. This book examines and presents select analyses of the background, scope and success of the AQI, with a focus on management challenges and inspection fees.