Section 139 of the Constitution of South Africa empowers provinces to intervene into municipalities, an instrument to correct serious failures in local government. This article discusses the policy and legal framework for interventions and assesses whether the constitutional provisions that circumscribe it, are being adhered to. The starting point is that decentralisation, of which this instrument is part, is rules-based and that adherence to the rule of law is critical for its success. By its very nature, intervention represents an intrusion into the institutional integrity of the affected municipality and adherence to the constitutional safeguards surrounding the intervention is therefore critical. The article sets out the constitutional framework for interventions into municipalities which includes oversight roles for the Minister responsible for local government, the National Council of Provinces and the provincial legislature. It combines this with an assessment of 39 interventions that took place between 2008 and 2014. It presents a provincial breakdown and a breakdown of the legal basis of these 39 interventions. It concludes that provinces don’t use the interventions envisaged in Section 139(4) and (5) but instead almost always intervene in terms of Section 139(1) of the Constitution. The interventions are assessed for compliance with constitutional prescripts, such as the need to establish a failure to fulfil an executive obligation, the timely submission of the intervention to the Minister and the NCOP and their timely approval.