This report provides a review of the literature on private security, including major trends, demographics, collaborations with law enforcement, budgeting and licensing, legal authority and powers within private security, and security operations. The report also presents an analysis of the availability and quality of secondary data on private security, including a review of the available private security data from government sources, commercial sources, and research or academic sources. The report examines the methodologies used to collect data on the private security industry, judges the quality of the available data, and assesses the value and feasibility of conducting one or more surveys of the private security industry in the United States. Opinions or points of view expressed are those of the author and do not necessarily reflect the official position or policies of the U.S. Department of Justice.