This manual, Army Doctrine Publication ADP 3-28 Defense Support of Civil Authorities February 2019, is the doctrinal foundation for the Army's contribution to defense support of civil authorities (DSCA). ADP 3-28 explains how the Army conducts DSCA missions and National Guard civil support missions as part of unified land operations. ADP 3-28 focuses on achieving unity of effort among the Army battalions, brigades, division headquarters, and Army Service component commands conducting DSCA with support from the generating force and in cooperation with joint and interagency partners. The principal audience for ADP 3-28 is all members of the Army profession. Commanders and staffs of Army headquarters serving as joint task force headquarters should also refer to applicable joint doctrine concerning the range of military operations and joint forces. In addition, trainers, educators, and contractors throughout the Army will also use this publication as a doctrinal reference.