D¿Ippoliti introduces the concept of diversity to summarise all differences that are of social origin and that a theory or model seeks to explain. This contrasts with the traditional concept of heterogeneity that instead refers to differences that are deemed to be exogenous of economic theory. In approaching this, the book ranges from the fields of methodology and history of economics to applied empirical work, as well as gender diversity which is considered in depth. The analysis of the thinking of two major economists of the past, John Stuart Mill and Gustav Schmoller, demonstrates how gender diversity exemplifies some of the fundamental issues in economics, such as the division of labour, society¿s capacity to reproduce itself, and the role of social institutions and their impact on individual and collective behaviour.