Local health departments are organized, resourced, and operated primarily for routine public health services. For them, responding to emergencies and disasters requires adaptation to meet the demands of an emergency, and they must reallocate or augment resources, adjust work schedules, and, depending on severity and duration of the event, even compromise routine service outputs. These adaptations occur to varying degrees regardless of the type of emergency or disaster. The Adaptive Response Metric was developed through collaboration between a number of California health departments and university-based preparedness researchers. It measures the degree of “stress” from an emergency response as experienced by local health departments at the level of functional units (eg, nursing, administration, environmental services). Pilot testing of the Adaptive Response Metric indicates its utility for emergency planning, real-time decision making, and after-action analytics.