Driving sustainable development through new products, services, techniques and organisational modes that substantially reduce environmental impacts, or ecopreneurship, is especially important for small and medium-sized enterprises (SMEs) as they have a vital role to play in managing limited environmental and social resources. Reaping the benefits associated with ecopreneurship, however, requires a fundamental qualitative change process at the firm level. However, there remains considerable uncertainty as to how ecopreneurs will discover, develop and realise sustainabilityrelated opportunities in their organisations. Thus, the purpose of this article is to address this gap by analysing how this qualitative change process associated with a shift to sustainable development actually unfolds in SMEs. To do so it examines small and medium-sized wineries in Austria. Based on the results of a Delphi study, a multi-layer process model that differentiates between unfreezing, changing and refreezing processes is developed. The framework shows that the unfreezing of the status quo is mainly accomplished by the business owner's attitude towards sustainability. In the course of the changing process, change related to the adoption of greener business practices follows a hierarchical order, starting with business activity (the first layer). Then, four dimensions of capital resources (the second layer) must be revised in order to implement the change successfully. After that, relevant stakeholders (the third layer) must be integrated into this iterative learning process. Finally, in the course of refreezing, change is embedded in the organisation by the ongoing commitment of the business owner and future sustainable expansion strategies. The developed framework may serve as a guideline for small and medium-sized wineries, but also for a broader set of SMEs implementing sustainable organisational change in the future. The framework could also be used by national governments or certification authorities uncertain of how best to support the change process in SMEs. (authors' abstract)