Local health departments are responsible for creating and maintaining conditions that keep people in their communities healthy and safe. The Centers for Disease Control and Prevention (CDC) has defined and recently updated 10 essential public health services that communities should undertake to protect and promote the health of all people in their community. This training uses a case study (based on an actual infectious disease outbreak) to relate each step of the investigation to one of the 10 essential public health services. Public health professionals should be able to describe each of these essential services, and should work to ensure that all 10 services are provided in their community.