The purchaser–provider co-operation model is a way of increasing efficiency and quality in healthcare services. Risks associated with this model, including goal misalignment and information asymmetry, are managed through control mechanisms. Based on data from 12 clinical commissioning groups (purchasers of cancer care) in the English National Health Service, this paper describes the control mechanisms used to facilitate purchaser–provider co-operation and identifies good practices in using different control mechanisms. Effective control mechanisms were found to include stakeholder involvement (social control); co-operation and partnerships with providers (process control); and monitoring and service outcome measures for provider (outcome control). The paper fills an important gap in the literature—little scholarly attention has to date been paid about how purchaser and provider relationships are managed ex post and how performance is affected.