Businesses have a critical role in the transition to a sustainable economy, but this requires them to include social and environmental considerations in their decision-making. However, this creates the problem of resolving competing economic, social and environmental commitments over the long and short term. Scholars have examined this either as an analytical or a cognitive problem, but these approaches may understate the importance of organisational influences. This thesis therefore addresses two questions: first, how do the formal, behavioural and social structures of an organisation interact to influence the inclusion of sustainability criteria in decision-making in incumbent businesses? Second, what are the points of intervention to influence these systems? To answer these questions, I undertook three connected empirical studies, using mixed qualitative methods.

These investigations produced four findings. First, including sustainability changes the nature of decisions, leading to four specific archetypes of decisions. Second, the way in which decision-makers resolve the competing commitments in these situations is shaped by a broader framing of the tension between the fundamental logic of the business and the demands of its environment. Third, decision-making is influenced by a series of contextual factors, including the properties of the decision itself; the decision maker(s); the organisation; and the broader environmental context. Fourth, the process of changing decision-making requires a combination of interventions, and a set of foundational capabilities to change. Companies undertaking this type of change find systemic barriers that can only be resolved through co-operation beyond the boundaries of the organisation. These findings have implications for practice.

This research contributes to the literature on decision-making and sustainability by presenting a novel classification of decisions and by adding detail to the understanding of contextual factors influencing decision-makers and to paradox theory by demonstrating the influence of paradoxes on decision-making logic and on driving change. This matters: corporate sustainability is an enacted process and unless business decision-making changes, we will not be able to achieve the social and environmental change we need.