Information systems development is driven by a variety of stakeholders – each with specific requirements. Modern agile development methods, like Scrum, allocate the vital step of prioritizing requirements to dedicated roles like the product owner. However, this can create a bottleneck and may lead to misunderstandings and conflicts between stakeholders. Enabling stakeholders to cooperatively prioritize requirements frees up product owners while involving stakeholders more closely in a crucial development step, strengthening their ties to the final system. Therefore, stakeholders must form a mutual and shared understanding of requirements. This research in progress utilizes the design science research methodology to propose design principles for a cooperative requirements prioritization system using the MuSCoW method – which classifies requirements in four categories. By transferring the theory of shared understanding to the field of requirements prioritization, we derive design principles for cooperative requirements prioritization systems. We enable a group of heterogeneous stakeholders to identify and discuss differences and come to a mutually-agreed prioritization decision. ... mehrWe introduce design features that instantiate these principles and present promising results of an initial pre-test. This research in progress contribute to information systems development by introducing principles for the under-researched, but important class of requirements prioritization systems.