AbstractSystem of Systems (SoS) architecting requires analyzing a set of individual but interconnected systems simultaneously in order to build a communicating SoS, which can provide the capabilities needed. In general, the systems can provide a set of capabilities and the SoS architect needs to decide which systems to include in the SoS so that each capability is provided by at least one system. In this case, the systems are inflexible, i.e., a selected system will contribute to the SoS with all the capabilities it can provide. On the other hand, if SoS architect can incentivize systems to contribute specific capabilities instead of all its capabilities, it might be possible to build a better SoS in terms of not only one objective but all objectives considered. In this study, we compare SoS architecting with inflexible and flexible systems and quantify the value of the flexibility of the systems for a military application. Two evolutionary algorithms are constructed for the SoS architecting with inflexible and flexible systems for the resulting multi-objective optimization problems. These evolutionary algorithms output a set of Pareto efficient SoS's for the architect. Upon comparing the Pareto fronts of inflexible and flexible models, we quantify the value of systems’ flexibilities. It is demonstrated that SoS architecting with flexible systems can improve performance while decreasing costs.