I consider myself a mainstream researcher in the field of business policy, and the ideas I want to describe in this paper concern the foundations of a theory of business strategy that is rooted in economics. But is such a paper, whatever its merits, really appropriate at a conference entitled 'Non-traditional Approaches to Policy Research'? Surprisingly, it is. The use of economic theory to model and explicate business strategy, as it is understood within the field of business policy, is distinctly non-traditional.