Amartya Sen argues that ''the standard of living'' has been poorly understood and narrowly defined; it is not just a function of opulence, and cannot be seen as utility. It is, he suggests, the ''capabilities'' offered in states of affairs. In his comments, Bernard Williams considers the conceptual connections among Sen's capabilities, economic welfare, and the broader notion of ''well-being'', and asks whether the notion raises questions of justice. Ravi Kanbur considers the implications of the uncertainty in the choice that might be thought to be one desirable capability. John Muellbauer offers a specification of choice, and discusses the importance, for assessing capabilities, of the relation between preferences and constraints and between preferences themselves. Keith Hart explores the issue for those societies in which economic life is not fully ''commoditized'' and in which, therefore, it does not always make sense to reduce things to a price. Sen concludes with replies to these comments.