The U.S. Department of Defense (DoD), from its most-senior leaders to military operators in the field, has expressed a strong commitment to complying with the law of war and to mitigating civilian harm for legal, moral, and strategic reasons and for reasons related to mission-effectiveness. But above and beyond its law of war obligations, DoD implements policies and procedures at multiple levels to mitigate civilian harm during armed conflict. In this report, researchers from the RAND Corporation and the Center for Naval Analyses (CNA) conduct an independent assessment of DoD standards, processes, procedures, and policies relating to civilian casualties resulting from U.S. military operations. In particular, the researchers examine DoD's efforts to assess, investigate, and respond to civilian harm, as well as DoD's resourcing and structure to address such issues. The researchers outline their findings and recommendations for how DoD can improve in these areas.