Private military and security company (PMSC) employees are not soldiers, but their activities often place them in conflict zones. Their presence has complicated efforts to ensure the effectiveness of international humanitarian law (IHL) in fluid situations involving state and nonstate actors. This chapter explores how PMSCs fit in the framework of IHL and the broader legal framework governing PMSCs, along with state and international efforts to ensure PMSC compliance with IHL. Critical issues concern the status of PMSC contractors under IHL, which determines the protections they should be accorded; their training in the laws of war; and the rules regarding the use of force under which contractors operate. The legal framework holding PMSC employees accountable remains uneven in its global reach, and voluntary frameworks have emerged to develop and enforce good business practices and adherence to human rights standards. Whether these measures will be effective remains to be seen.