Large organizations play a key role in sustainability transitions through their systems of production and consumption and their influence on wider society. Recognizing the uniqueness and complexity of structure-agency relations in organizations, this paper uses the example of food provisioning to compare the sustainability potential of eight national and multinational organizations located in Ireland. By introducing the novel concept of ‘alteration spaces’ to describe specific intra-organizational structure-agency constellations and their dynamics over time, we question existing interventionist views of organizational change. We argue these tend to overstate extra-organizational impulses for change while paying insufficient attention to organizational culture and committed individuals as potential sustainability advocates within organizations. This, in turn, facilitates a reconceptualization of individual agency as embedded within an organizational context, thereby challenging dominant understandings that disregard the potential of established organizations to initiate intra-organizational changes that shape and reflect sustainability transitions.