Prioritization is critical for process decision-making. Organizational decision-makers frequently do not have clear perceptions of which processes are of prime and secondary importance. Research does not provide a satisfactory definition of process importance and quantifiable proxies. This paper derives dimensions of process importance including the number of process executions, process participants, customer and supplier involvement, and value chain position from literature, and introduces measurable proxies from information systems for each dimension. We retrieve 220 processes from 52 process experts across four real-world companies. 773 ERP transactions are matched to the processes to measure which processes constitute important processes along importance dimensions. The artifact “KeyPro” is developed to explore important processes bottom-up from log data in an SAP-ERP system with visualization in interactive dashboards. We implemented KeyPro in three real-world SAP-ERP systems and a focus group of process experts. An evaluation in two case studies reveals significant deviations between perceptions by decision-makers and results suggested by KeyPro.