When communities are subjected to disruptive events, their response structure is composed of two interconnected systems: (i) a formal professional system that includes emergency services and auxiliary services professionals; and (ii) an ad hoc system formed by community members when the professional response is delayed or is inadequate. The community system typically persists until the professional system is able to take over completely. As the role of the community as responder is not well understood, community systems are often underutilized or even discouraged; this reduces the overall response efficacy. Improved understanding of the interplay between these systems could help ensure an effective overall response to disruptions.This chapter describes an integrated, multidisciplinary model of the interactions between the two systems during disruptive events and their influence on capacity and recovery. The model studies how the systems influence and enable community resilience in the context of three Department of Homeland Security defined sectors: emergency services, information technology and communications. The methodology combines agent-based modeling with cellular automata and illustrates the interplay between and among the people and systems that make up a community, the role of the community as responder and the impact of varying community resources and response capabilities. The model is designed to be transferable to a variety of disaster types and a hierarchy of jurisdictions (local, regional, state, national and international).