While a number of studies document that organizations go through numerous stages as they increase their commitment to sustainability over time, we know little about the role of the Chief Sustainability Officer (CSO) in this process. Using survey and interview data we analyze how a CSO's authority and responsibilities differ across organizations that are in different stages of sustainability commitment. We document increasing organizational authority of the CSO as organizations increase their commitment to sustainability moving from the Compliance to the Efficiency and then to the Innovation stage. However, we also document a decentralization of decision rights from the CSO to different functions, largely driven by sustainability strategies becoming more idiosyncratic at the Innovation stage. The study concludes with a discussion of practices that CSOs argue to accelerate the commitment of organizations to sustainability.