In this Element, emerging legal forms of purpose-driven corporations are analyzed, revealing two important insights. First, within the traditional corporate law, a purpose is neither protected nor enforceable over time. While companies can have goals beyond profit, these are controlled by shareholders, who also appoint corporate managers. To protect social or environmental ambitions, especially during shareholder changes, a legal commitment from the company is essential. Second, these new legal forms highlight the need to redefine the corporation's legal foundations. In an era when management decisions impact entire populations and the planet, the law inadequately conceptualizes the conditions necessary for responsible management. The Element argues that embedding a purpose in the constitution of corporations can provide these new legal foundations. Ultimately, the Element suggests that purpose provides a unified theoretical framework for understanding the variety of corporate legal forms and for discussing their respective potentials and limitations in holding corporations accountable in the face of upcoming transitions.