The aim of our paper is to investigate the mechanisms adopted by cities to control the provision of externalized public services and explore the determinants of such control choices. To this aim it presents the results of a multiple case study based on the experiences of three cities and three public services (transport, solid waste collection and home care services for the elderly), where we analysed control mechanisms and their possible antecedents. Our results show that the control models found in the cases analysed do not correspond to the ‘pure’ patterns described in the private sector literature and that the factors identified by management control contributions do not seem to be exhaustive in explaining the configuration of control systems in the public sector. While environmental and task characteristics only partially explain the adoption of certain configurations of control, the features of the control systems seem to be rather influenced by variables that are related to party characteristics. The results show that the combinations of control mechanisms are more multifaceted than those presented in the literature, and that the factors identified in the private sector literature do not seem to explain comprehensively the configuration of control systems in the public sector.