This paper offers an alternative theoretical structure to the neoclassical valuation model that has been the cornerstone of theories of finance for a quarter of a century. It begins by outlining the neoclassical model in simple but surprisingly robust terms. More recent extensions and refinements are then discussed. The alternative model, which does not rely on modern financial economic theory but which is consistent with real world empirical behaviour, is developed next. Finally, a new research agenda for finance is proposed.