Project success is one of the most studied topics in project management. Notwithstanding this vast literature base, project results continue to disappoint stakeholders. Turner and Cochrane (1993) argued that the traditional measure of success, completing the project on time and within budget, is based on the assumption that in projects both the goals and the method of achieving them are well understood at the start of the project. For some projects however, the objectives and/or the methods are not clearly defined. These projects are only successful if they achieve a unitary, beneficial change with value for users. A domain that has great experience in dealing with these type of problems, where only the aspired end value is known, not the goals and methods, is Design Thinking. The study reported in this paper explored the question What aspects of the Design Thinking approach should be integrated into Project Management in order to contribute to the successful management of projects? Based on an analysis of the literature, we developed a conceptual framework that characterizes the differences between the Rational Analytic approach and the Design Thinking approach to projects. We deployed an experimental research strategy to empirically explore what new insights a design thinking approach gives to project managers. Our findings indicate that with the aid of a Design Thinking tool, the project managers were able to adopt a design thinking approach. In applying this approach, they played an active role both in the problem definition phase of the project and in synthesizing new solutions that create value for users. Based on the insights gathered from the experiment, we propose that the following three aspects of Design Thinking should be integrated into Project Management: 1. Framing and reframing, 2. Focus on the wants and needs of users and 3. Use of visual aids.