Field Manual (FM) 3-57, Civil Affairs Operations, provides the doctrinal basis for the conduct of operations in support of the joint force commander's (JFC's) civil-military operations (CMO) concept. It provides Army commanders with the information necessary for the integration of Civil Affairs (CA) capability in support of unified land operations. 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. 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).