Contemporary armed conflicts have increasingly been accompanied by belligerents’ calls for civilians to support their military efforts. This article investigates the legal consequences of civilians taking up arms provided by or with the tacit support of the State. It first looks at the implications of civilian involvement from the perspective of a State's international humanitarian law (IHL) and international human rights law obligations, focusing on removing civilians from the vicinity of hostilities, informing and training civilians on the implications of directly participating in hostilities, and respecting and ensuring respect for the law. It then demonstrates that the broader fabric of public international law is tested when civilians are encouraged to engage in hostilities, through a close analysis of the challenge of attributing civilian acts to the State. The article closes with practical recommendations for States to ensure that they uphold their humanitarian and human rights obligations, and to render the law of international responsibility effective when civilians commit systemic violations of IHL.