Maturity models represent a feasible approach towards assessing business processes and identifying their potential improvements. Specifically, the Process and Enterprise Maturity Model (PEMM) has attracted much attention since its publication in 2007. However, few studies have explored its practical applicability. The large size of some business processes suggests that assessing their maturity at a sub-process level can help to uncover hidden inefficiencies and understand more accurately existing complexities. This paper therefore aims to examine the degree of applicability of the PEMM to an individual sub-process. To this end, an action research study was conducted in an organizational sub-process at a large Swedish organization. Data collection entailed in-situ participant observations involving employees and managers who were working in the sub-process. The results indicate that the PEMM was a useful framework for conducting an in-depth maturity analysis and identifying feasible improvements, which evidence that the model was applicable to the studied sub-process.