Discrete Event Simulation (DES) is widely used in analyzing and improving business processes. Business process maturity models (BPMM) are used to define maturity levels of business processes and give recommendations how maturity levels can be increased. While each has proven their efficiency in their own way, very little attention is paid to the complementary role they play when combined. In this paper, we discuss and demonstrate the added value of simulation in conjunction to maturity models. The quantitative added value of simulation models as well as the added value in change management are discussed. We used two case studies from a large financial organization to demonstrate the added value of simulation in conjunction to BPMM. The finding of this research resulted in a set of recommendations about suitability of DES at different maturity levels. Furthermore recommendations are given for further research in the field of maturity levels supported by simulation.