This chapter examines states’ obligations in relation to disappearances committed by non-state actors under International Human Rights Law. It begins by analysing obligations under a variety of human rights instruments relating to the different rights that can be violated as a result of a disappearance committed by a non-state actor, such as the rights pertaining to physical integrity. These encompass obligations to prevent, investigate and remedy. After briefly introducing the concept of positive obligations in relation to harm caused by non-state actors, the chapter explores how these obligations have been articulated in select case law involving disappearances committed by non-state actors, or cases that deal with similar situations, such as kidnappings or human trafficking. The analysis draws on jurisprudence of the Human Rights Committee, the European Court of Human Rights, and the Inter-American Court of Human Rights. The second part of the chapter focuses on the obligations of states under the International Convention for the Protection of all Persons from Enforced Disappearance, which is the only human rights instrument concerned with enforced disappearances that specifically establishes obligations in relation to disappearances committed by non-state actors. The analysis shows that states have clear obligations regarding the investigation of disappearances committed by non-state actors and holding those responsible to account. They should also take preventive measures. However, there continue to be gaps when it comes to the obligation to provide reparations to victims of disappearances committed by non-state actors, and their relatives, which requires a prior determination of responsibility.