According to the Department of Defense (DOD), the United States of America's competitors and adversaries are taking advantage of vulnerabilities in the information environment to advance their national objectives and offset the U.S.'s position as the preeminent warfighting force. DOD's military operations in the information environment play a pivotal role in engaging our adversaries. House Report 117-118 included a provision for US Government Accountability Office (GAO) to review DOD training that prepares leaders and service members to operate and make decisions in a contested information environment. In this report, the GAO (1) describes DOD guidance that supports the department's education and training efforts to prepare leaders to make decisions in a contested information environment and (2) assesses the extent to which DOD provides education and training designed to prepare leaders to make such decisions. GAO reviewed selected DOD strategies, policies, and course syllabi; analyzed information related to the conduct of military exercises; and interviewed officials with knowledge of the department's education and training efforts.