Oncology nurses are at risk for compassion fatigue, which is often assessed using the Professional Quality of Life Scale (ProQOL). Nursing researchers and leaders use the ProQOL to determine risk for compassion fatigue or effectiveness of interventions to reduce compassion fatigue. However, the ProQOL was designed for social workers, and research has shown it to be less suitable to assess the work of nurses. This article synthesizes a realist review of the literature about instruments measuring nurses’ professional quality of life (QOL). The following three themes emerged: (a) a robust body of literature aimed at defining professional QOL, (b) a limited historical context of the ProQOL instrument, and (c) newer instruments. Findings suggest that the ProQOL-21 and the Risk Factors for Compassion Fatigue Inventory are more specific to nursing and better suited to measure nurses’ perceived professional QOL.