Since 2008 the Universal Periodic Review (UPR) mechanism of the UN Human Rights Council has become a fixture of the international human rights regime, reviewing the human rights record of every single state once every few years. Over the course of the UPR reviews to date thousands of recommendations have been issued about the protection of human rights with a growing body of evidence showing that states modify their behaviour in response to the outcome of reviews. This chapter analyses how UPR recommendations can be used to identify customary international law. Using the discussion on the identification of custom in General Assembly resolutions as a starting point the chapter examines how scholarship on the identification of custom has argued that there are a different set of rules for the identification of customary international human rights law. Identifying custom in UPR recommendations can help resolve some of the ambiguities and contradictions in relation to the identification of customary international human rights law. This chapter concludes by outlining a three-part model for identifying custom in UPR recommendations which would complement existing rules for identifying customary international law.