This chapter attempts to set forth clear categories for the legitimate employment of military forces in support of civil authorities. Soldiers can expect increasing calls from civilian authorities for their services. It examines in depth the full range of missions, tasks and functions for each of these rubrics, and provides examples of such operations as conducted across a broad range of states, both in Europe and in North America. The six categories are designed to be sufficiently inclusive so that they are distinctive in identity and comprehensive enough, but at the same time relatively exclusive in order to avoid duplication, even though there is some inevitable overlap. The chapter explores examples of the kinds of Defense Support to Civil Authority (DSCA) operations that have been conducted by Western military forces, and also provides sufficient detail regarding the kinds of individual functions and tasks that these operations may require.