The client and contractor have to take on a new role in Best Value projects, and this is not as comfortable or intuitive for everyone. People can behave irrationally in conflicts, but conflicts are bound to happen in projects. The objective of this research was to design a set of actions to prevent conflicts in Best Value projects. The first part of the research focused on identifying the main causes of conflict in Best Value projects. The data was gathered through semi-structured interviews with fourteen project managers from clients and contractors to understand how conflicts originate and evolve in Best Value projects. The analysis showed two causes of conflict in Best Value projects. (1) The lack of involvement of the client’s client leads to unnecessary process- and technical-related conflicts during the execution phase. Often the conflicts occur after tasks are completed, and the hand-over takes place. (2) Best Value forces the contractors to prove their trustworthiness towards the clients. However, contractors often do not continue to prove their trustworthiness, which makes the client anxious. This will lead to traditional and controlling behaviour. A set of actions was designed to help contractors and clients to prevent conflicts in the execution phase of their Best Value project. The interviews and expert sessions are the input for activities that could be used. These activities were analysed to identify actions for the clients and contractors in Best Value projects. The actions focus on making sure that the client’s departments can be involved in the projects or on building cognition-based trust during the project.