Mitigation creates the basis for community resiliency by lessening the disaster’s toll on the physical environment. For example, the contrasting outcomes of earthquakes in Chile and Haiti demonstrate the value of physical mitigation through building codes and engineering. Policy interventions and governmental mechanisms can enhance the likelihood of mitigation steps being taken in advance of disaster, which in turn improves the resiliency of communities. California’s seismic activity in populated areas has led to the creation of mitigation measures for schools, hospitals, residential and commercial buildings, and infrastructure, which grew from multi-disciplinary collaboration. This collaborative approach is embodied in the California Seismic Safety Commission, which oversees the state’s hazard mitigation plan. The commissioners include representatives from science, engineering, emergency management, and social services who can apply their expertise to the evaluation of potential mitigation measures, work with the legislature for passage and funding of mitigation measures, and work with local governments for the implementation of policies and programs to create resiliency. This chapter evaluates the contributions of multi-disciplinary collaboration to the development of resiliency in California as a model for other states and nations confronted with intractable natural hazards.