Field Manual (FM) 3-57, Civil Affairs Operations, provides Army commanders with the information necessary for the integration of Civil Affairs (CA) capability in support of unified land operations. It provides the doctrinal basis for the conduct of operations in support of the joint force commander's (JFC's) civil-military operations (CMO) concept. FM 3-57 clarifies the role of CA forces in support of CMO with regard to the missions, employment, support requirements, capabilities, and limitations of these forces. CA forces support missions in every theater, in peace and war, throughout unified land operations. CA forces are a combat multiplier for every commander. CA forces are one of the primary resources a commander has to assist him in dealing with the complex and ever- changing civil component of the operational environment. CA forces are trained, organized, and equipped to plan, execute, and assess the JFC's concept for CMO. They are essential elements in the support of the commander by virtue of their area and linguistic orientation, cultural awareness, training in military to host nation (HN) advisory activities, and civilian professional skills that parallel common government functions. The principal audience for FM 3-57 is the leadership of the Army, officers and senior noncommissioned officers who command Army forces or serve on the staffs that support those commanders of operations at all levels of war. It is also an applicable reference to the civilian leadership of the United States (U.S.) interagency organizations. Although written primarily to assist the Army Service component command (ASCC), Army corps, Army divisions, brigade combat teams (BCTs), and maneuver enhancement brigades (MEBs) with the integration of Civil Affairs operations (CAO) in planning, preparing for, executing, and assessing unified land operations, this FM is applicable for joint force operations as well. The commander must always consider the engagement of the civil component within the area of operations (AO). Commanders, staffs, and subordinates ensure their decisions and actions comply with applicable U.S., international, and in some cases, HN laws and regulations. Commanders at all levels ensure their Soldiers operate in accordance with the law of war and the rules of engagement (See FM 27-10). FM 3-57 uses joint terms, where applicable. Selected joint and Army terms and definitions appear in both the glossary and the text. Terms for which FM 3-57 is the proponent publication (the authority) are marked with an asterisk (*) in the glossary. Definitions for which FM 3-57 is the proponent publication are boldface in the text. These terms and their definitions will be in the next revision of FM 1-02. For other definitions shown in the text, the term is italicized and the number of the proponent publication follows the definition. FM 3-57 applies to the Active Army, Army National Guard/Army National Guard of the United States, and United States Army Reserve unless otherwise stated. The proponent of FM 3-57 is the United States Army John F. Kennedy Special Warfare Center and School (USAJFKSWCS).