Organizations are increasingly working on business processes improvement to meet stakeholders’ requirement. Process engineering and improvement projects are challenged by identifying proper metrics to guide improvement effortsand mitigate process complexity. This latter is intuitively related to factors such as usability, modularity, reliability and maintainability. A process that is too complex is more likely to fail and produce costly quality problems. In a context of collaborative decision-making, complexity management must consider the expectations of several stakeholders, and the definition/use of suitable metricsis the starting point. The current paper identifiesandusesa set ofmetrics to enable the evaluation of process models. The proposed metric system is used within a case study highlighting the key role of modularity inmitigating processcomplexity.More generally, the results show how using the metric system can support complexity mitigation and therefore performance improvementin (re)engineered processes.