This chapter debates the appropriateness of the Paris Agreement’s ‘compliance’ system. The treaty’s Article 15 establishes ‘a mechanism to facilitate implementation of and promote compliance with the provisions of this Agreement’. Views differ radically on the legal mandate of this mechanism and its capacity to ensure that states comply with their treaty obligations. Meinhard Doelle praises the mechanism’s ability to sensitively inform domestic political and legal processes and, thus, to increase the likelihood of an effective implementation of states’ obligations. Anna Huggins develops the argument that an effective compliance system comprises both facilitation and enforcement elements, yet the Paris mechanism limits itself to facilitation. Moreover, in its facilitative role, the mechanism is duplicative of other facilitative elements of the Agreement.