Traffic congestion has proven to be a wicked problem that is affecting people's economy and health. Until now, traditional policies have not yet been able to solve the problem entirely. To tackle such a challenge, new innovative measures are needed. Mobility as a Service (MaaS), a new paradigm in mobility where all modes of transportation are offered to the user in packages through a digital platform, offers a new approach with a service that could compete with private car ownership, the main cause of traffic. However, there is no policy research on the implications of MaaS and whether an intervention from the government is necessary to boost the reduction in traffic congestion in this new paradigm. MaaS is a system full of uncertainty and it's adoption is a time changing complex process. System Dynamics is an interesting method to close the research gap identified, since it is commonly used in time changing systems with high uncertainty. However, this is a method not commonly use for the study of mobility, and there is a need to identify the challenges when using this method. The main objective of this thesis project is to evaluate the use of System Dynamics as a research method to understand MaaS.