This project deals with the antecedents and consequences fo demographic diversity in the realm of teams, organizations, industries, networks and communities. Demographic diversity refers to groups of people or organizations. Both can be more or less diverse in terms of e.g. age, gender and personality (people) or age, size, strategy (organizations). The key questions are where this extent of diversity comes from and what it implies for the behaviour and performance of the social entities involved. The proposed research programme is groundbreaking by providing centre stage to demographic diversity of social entities. Moreover, it is unique in its multi-method, multi-disciplinary and multi-level approach. First, theory will be developed by building models using mathematical and simulation techniques, whilst the empirical studies will analyze novel panel datasets by applying advanced multivariate statistical tools. Second, insights from different economic and social science disciplines will be combined and integrated, notably economics, public administration, economics, economic geography, political science, psychology and sociology. Third, the multi-level perspective will be explored systematically, implying that interactions across different levels of analysis will be investigated.