Technical Abstract: The first line of defense against exotic pests is exclusion. For citrus, this is achieved by quarantines and a requirement that all citrus germplasm introduction to California pass through the California Citrus Clonal Protection Program, University of California, Riverside. Here, all new germplasm received is tested for disease agents, treated by thermotherapy and/or shoot tip grafting to eliminate pathogens and propagated on clean rootstocks. Introductions are subsequently retested to insure pathogen-free and true-to-type status before distribution to the citrus industry or public. Trapping for exotic Tephridid fruit flies, glassy-winged sharpshooter, light brown apple moth, Asian citrus psyllid, and surveys for Citrus tristeza virus and septoria spot are described as examples of interior surveys. The Navel and Valencia Export to Korea (NAVEK) program is discussed to show how a systems approach may be used to maintain a foreign market with quarantine restrictions. When an exotic pest is found, delimitation surveys are deployed to determine extent of infestation and risk assessment. This is followed by appropriate mitigation efforts such as eradication, biological control and pest management. Such efforts require coordination of different agencies, researchers, growers and public support.