The term 'social innovation' has come into common parlance in recent years. Some analysts consider social innovation no more than a buzz word or passing fad that is too vague to be usefully applied to academic scholarship. Some social scientists, however, see significant value in the concept of social innovation because it identifies a critical type of innovation. In this paper, we suggest one possible definition of social innovation and show that when its empirical meaning is distilled, the term is of great importance. We distinguish social innovation from business innovation, and identify a subset of social innovations that requires government support.