Organizations, such as social enterprises, engage in business model innovation when they wish to create, deliver, and capture value for their various stakeholders in ways that effect positive environmental and social change. Despite the increasing research attention paid to social enterprises, the literature on business model innovation in this context is still scarce. Therefore, the purpose of this paper is to explore business model innovation driven by sustainability issues at a social enterprise operating in the Scandinavian electricity retail market. A single case study research approach is taken, and data are collected from sixteen individual interviews and two focus groups with executives, managers, and directors. The study contributes to business model innovation as an organizational change process as well as an outcome of this process. The findings show that business model innovation over time at social enterprises reflects a shift in focus from novelty, via lock-in of customers, to efficiency in internal management routines. Additionally, the study concludes that social enterprises with innovative business models driven by sustainability issues can introduce novel practices that lead to changes in the dominant business model of their industry. The study also suggests how social entrepreneurs might innovate their business models as they focus on environmental and social sustainability. © 2017 Elsevier Ltd. All rights reserved.