Private security companies (PSCs) have experienced explosive growth since 2001, growth that has been matched only by the consequent explosion in academic attention probing their influence. It is not hard to discover that PSCs and their employees constituted the second-largest member of the US-led Coalition of the Willing during the invasion of Iraq in 2003;1 that this represented a 10-fold increase compared with the first Gulf War in 1991;2 that there are between 15,000 and 50,000 contractors currently operating in Iraq, according to various estimates;3 and that these companies suffer, at the very least, from a dearth of effective regulation4 that some go as far as to call a vacuum.5 However, there has been very little analysis of the consequences of the use of such companies in civil wars. PSCs have the potential, because they are non-state actors, privately motivated, and often external to the conflict, to complicate civil wars. Indeed, the use of PSCs by the US (by far the largest employer of contractors, as PSC employees are often called) has been characterised by a notable absence of planning and policy, both military and governmental. The United Kingdom, which is host to a number of major companies, has similarly failed to examine the policy consequences of the private security industry. This article examines how the absence of effective policy about the effects of privatising force has led to a series of unintended consequences that are influencing and will continue to influence the nature of civil wars. The first section begins by briefly outlining the nature of the private security industry and the roles it plays in civil wars. The second section examines how poor planning has led to problems for the US in its interventions into civil wars, focusing particularly on the private security industry in Iraq. The third section addresses how a similar lack of policy has caused the UK difficulties in the past, and could mean the UK will face problems in conflicts in the future.