This paper looks at what the value of a doctorate is, both to employers in particular and to society and the economy at large. Given the emphasis many universities and funding agencies/governments are putting upon the development of PhD programmes, this is an issue deserving attention. The paper tries to show how two separate but interrelated questions "What is a doctorate worth?" and "Is there a justification for society to subsidise the production of doctorates?" might be answered. It considers the argument that the production of PhDs can generate benefits for wider society--both because the production process itself generates basic knowledge from which all can take advantage and because the outputs of that process help boost the productivity of those with whom they work. In other words, the gains to society as a whole might be greater than the sum of gains to PhD holders and their immediate employers. Evidence is reviewed. (Contains 1 table.)