This paper clarifies the status of the firm vis-à-vis the Rawlsian basic structure of society. This status is ambiguous due to uncertainties in Rawls’s conception of the firm and his definition of the basic structure. The paper identifies two perspectives regarding the firm in Rawls: an inclusivist perspective defines the firm as an entity ontologically distinct from the basic structure; while a constitutivist perspective views the firm as an institution that possibly forms part of the basic structure. The paper then reviews several interpretations of the basic structure before offering a more inclusive version, which notably includes some informal structures. Linked to the institutionalist conception of the firm, this expanded definition of the basic structure results in an extended constitutivist perspective regarding the firm. It thus provides liberal egalitarianism with firmer ground for critically assessing businesses.