The San Diego County Animal Disease Diagnostic Laboratory (ADDL) is unique in its emphasis on protecting both human and animal health in San Diego County, and its use of interagency and community collaboration to create strong, effective public health programs. This article describes the ADDL core programs of avian and vector-borne disease surveillance, rabies testing, and animal abuse investigations and uses selected case studies to illustrate the need for a local veterinary diagnostic laboratory to safeguard the health of humans and animals. The ADDL serves as a role model for other local communities to develop vital public health partnerships to ensure a healthier community.