This paper aims at contributing to the recent literature about the internal dynamics of sustainability. The specific research question addressed in this paper is: how do various organizational actors understand and make sense of sustainability in their workplace? To answer this research question a case study was prepared by focusing on IREN, an Italian listed multi-utility operating in the electricity, gas, and energy district heating, integrated water service and waste sectors, with considerable engagements with sustainability work. Data was collected through a combination of methods, i.e. interviews, e-mail exchanges, observations and document study. Findings reveal that sustainability has multiple meanings and various organizational actors interpret it differently depending on their role within organizations. Different interpretations of the concept of sustainability are also reflected in how sustainability is implemented and monitored. Multiple expectations explain why sustainability is difficult to integrate in organizational practices.