This article looks at how managers in large infrastructure projects in The Netherlands deal with difficult choices, which are labelled dilemmas in this article, in their managerial activities. It presents the results of a survey of 32 managers in 18 complex decision-making projects in which public—private partnerships (PPPs) play an important role. The managers were presented with a number of choices and asked to rate the amount of attention they paid to each of the choices. The article focuses on four (groups of) dilemmas managers face in the inter-organizational context of these processes: (1) interaction with parties, (2) strategic orientation, (3) management style and (4) process dynamics.After a brief elaboration of the role of (network) managers in complex PPP projects and the nature of the dilemmas they face, the four groups of dilemmas are explored by looking at how managers scored on the dilemmas within each group. Conclusions are drawn about managers' perceptions of these dilemmas and the differences between projects. The different choices of dilemmas are then compared with the differences between the scores of the outputs of the projects as perceived by the managers. Finally, general conclusions are drawn about the dilemmas chosen by managers and the consequences of these choices.

Points for practioners

Pay attention to commitment, goal searching, communication and vertical relations if you want good outcomes in complex environmental projects. Do managers of complex spatial and environmental projects in general choose to open up the decision-making process for stakeholders to enhance support and use the knowledge of stakeholders or do they choose a more closed decision-making process that reduces the number of actors and might speed up the decision-making process? In general, one can see many of these managerial choices between a more project oriented style, that focuses on control, specifying goals, keeping the budget, etc., and a more process oriented style that focuses on activating actors, creating support, or exploring possible content. If we look at the 32 managerial strategies that were researched, there are a few strategies that are positively and strongly correlated to positive perceived outcomes of projects: commitment, goals searching, vertical relationships and communication