This article examines attribution of conduct and responsibility in peace support operations, which is, and will continue to be, a troubling subject of international law. It particularly examines two specific questions: what is the proper test for attribution of conduct, and whether and, if so, how dual attribution of conduct and responsibility can be established in international joint operations? As regards the former question, a brief critique of the major case law and documents recently dealing with attribution of conduct and responsibility in peace support operations shows that Behrami and Saramati poses a serious obstacle to determining the most suitable test without any confusion, thus there is a strong need to radically depart from this decision of the European Court of Human Rights. With respect to the latter, the meaning of the 'effective control' criterion, which is to be the basis for dual attribution in joint military missions, ought to be clarified. In this respect, the Mustafić and Nuhanović judgments delivered by The Hague Appeal Court and the Supreme Court of the Netherlands, to which the article pays special attention, are exemplary – to the extent that the latter did not conflate the notion of dual attribution of conduct with that of (dual or) multiple attribution of responsibility – and these judgments can be seen as a source of inspiration for the future application of the ‘effective control’ standard in practice.