In recent decades, the world has seen an unprecedented rise of actors who aim for businesses to contribute to sustainable development. These actors are located outside of the businesses they address through service practices. Business sustainability initiatives, standard setters, and consultancies are so prevalent today that they constitute an ‘industry’ in providing these services. As a sustainability service industry therefore, these actors fulfill a crucial function in modern-day societies aiming for sustainability transitions, by acting as change agents for the business community. However, it is not clear with what performance rationales the sustainability service industry addresses the business community, as academic knowledge about sustainability performance in businesses is itself in its infancy. Like business sustainability scholarship, the sustainability service industry appears to implicitly assume contingent effectiveness of its approaches.This thesis is a phenomenographic study of 21 business organizations operating along the automotive value chain. Its primary aim is to answer the question: How does sustainability performance occur in businesses? Phenomenographic studies describe phenomena by their diverse conceptions, meaning, how research participants understand and experience phenomena of interest. Accordingly, this study shows that businesses understand and experience sustainability performance in five different ways. The five understandings are:(1) sustainability performance as meeting customer and regulatory requirements;(2) sustainability performance as the reduction of operational costs;(3) sustainability performance as the mitigation of risks to the business;(4) sustainability performance as the prevention of risks to business operations; and(5) sustainability performance as innovation that enables the achievement of societal sustainability aims.The findings of the study result in two major implications for scholarship. First, the thesis discusses how sustainability performance in businesses can be theorized from a perspective of contingency. Novel propositions are presented which suggest, amongst others, that businesses’ following of conceptions of sustainability performance is contingent on risk profiles emanating from the organizational environment, and that the effectiveness of management approaches is contingent on their fit to the conceptions followed. Second, the discussion of the findings suggests that a prevalent phenomenon of conception mismatchingexists in business sustainability scholarship. Conception mismatching means that scholarship does, so far, not adequately relate researched phenomena to the actual experiences of studied businesses.Furthermore, the thesis proposes to advance sustainability performance in businesses as a new area of inquiry that nurtures a strong interest in the real-world implications of research findings. In making the first steps toward this aim, the discussion formulates five implications for the sustainability service industry, which, if followed, would lead to alterations in its practices for more effective changes in business operations. The five implications for a more effective enabling of sustainability performance in businesses are that actors of the sustainability service industry need to:(1) discontinue unconsidered assumptions of contingent effectiveness of management approaches;(2) differentiate between conceptions of sustainability performance when addressing businesses;(3) take into account the diverse ways in which firms operate within as well as across conceptions of sustainability performance;(4) increase risks to businesses to entice the development of novel solutions for the most pressing sustainability challenges;(5) understand and enhance their practices in accordance with their role in shaping as well as promoting certain conceptions of sustainability performance.