In this paper the author examines the role of labelling and certification schemes in the pursuit of policies to make production and consumption processes more sustainable. From a logical point of view, labels are conceived as claims put forward by sellers to inform buyers about certain characteristics of their products. In the case of sustainability, labels might identify relevant 'ideals' to approach and/or significant 'ills' to escape. Toulmin's argumentation theory is used to show how claims can be substantiated and challenged. Based on literature on the behaviour of the main stakeholders, the author discusses what labelling means for producers, consumers, policymakers and other groups in society. In the conclusions, attention is drawn to the way in which societal pressure might interact with market forces to shape the information environment for products and services. As a result, the role of sustainability labels might become more differentiated, varying from direct shopping aids to background quality assurances. © 2003 John Wiley and Sons, Ltd and ERP Environment.