This Handbook is a guide and reference for the development of Area Contingency Plans (ACPs) for environmental emergencies. While it is primarily intended for use by EPA emergency response program personnel, area contingency planning is necessarily an inter-agency process, and the use of this handbook to inform other agencies of EPA's planning process is encouraged. Because area plans are focused on specific geographic domains, with many physical and jurisdictional variables, there can be no 'one size fits all' plan format, but maintaining a national consistency in the basic content is important, particularly considering the statutory and regulatory requirements by which EPA and other agencies are bound. This handbook was developed by EPA's Area Planning Workgroup during 2011 and 2012 and incorporates the accumulated knowledge of years of contingency planning experience. Although ACPs are specifically mandated by the Oil Pollution Act of 1990 (OPA 90), EPA's responsibilities under other laws, including CERCLA, make an all-hazards approach to contingency planning desirable. The processes of planning for responses to all types of environmental emergencies (e.g., oil spills, hazardous materials releases, natural disasters) share common elements that have been demonstrably successful in major responses.