The purpose of this project is to investigate and compare how different types of collaborative procurement strategies may enhance project actors’ collaboration and their possibilities and incentives for improved efficiency and innovation in infrastructure projects. Furthermore, challenges and perceived barriers to implement these strategies are identified and discussed. Four types of collaborative procurement strategies have been investigated, described and compared: 1) collaborative Design-Build contracts, 2) early contractor involvement (ECI) based on consultancy contracts during design stage, and 3) long-term integrated contracts based either on Design-Build-Maintain (DBM) contracts or 4) Design-Build-Finance-Maintain (DBFM) contracts. The paper draws on empirical data collected through interviews in 10 infrastructure projects in Sweden and the Netherlands. Our findings indicate that the collaborative procurement strategies influence four dimensions of collaboration (i.e., Scope, Depth, Duration, and Intensity), which in turn influence efficiency and innovation related aspects. Because implementation of these types of collaborative procurement strategies involves organizational change for all key actors, it is critical to adopt a long-term learning perspective when developing and implementing them. This study identified vital potential improvements of efficiency and innovation as a result of the chosen procurement strategies. However, due to the challenges of reaping all the potential benefits of collaboration, all actors need to continuously improve their processes, routines and capabilities for managing collaborative projects. ; Effektivitet och innovation i samarbetsavtal