Private delivery, i.e. contracting out, of maintenance services in urban parks and green spaces has since the 1980s been spurred by neoliberal reform promises of improved performance. This article contributes to discussions of whether contracting out park and green space maintenance services is a well-performing alternative by evaluating what is knownand not knownabout the outcomes in a narrative review of thirteen studies bridging experiences from four decades and three country contexts. It is found that the balance of reported economic and managerial outcomes mostly are on the positive side while the balance of reported outcomes related to service quality and staff are found to be on the negative side. Findings indicate that reforms have partly delivered on their promises. However, the reviewed studies are found to be dominated by evaluations based on governing values inherent in neoliberal management reforms rather than alternative management paradigms, rely on older data from a limited number of country contexts, and lack an accumulated understanding of explanation of outcomes. Finally, the reviewed studies pay little or no attention to the details of the development of different contracting and organizational models within contemporary urban green space management. Future research can expand further on what is known by addressing these key caveats.