Diversità nei gruppi di lavoro e performance - The key question in diversity research concerns the effects of diversity on Work Group processes and work group performance. In this setting most of research has been performed according to two distinct perspectives, the social categorization and the information decision making. So far however, the research has yielded ambiguous results: diversity seems to have positive as well negative effects on work group work group outcomes (Milliken, Martins, 1996; Brewer, 1995; Guzzo, Shea, 1992; Jehn, Northcraft, Neale, 1999; Triandis et al.,1994). Recently, van Knippenberg, De Dreu, Homan (2004) proposed the Categorization Elaboration Model CEM (van Knippenberg et al., 2004; van Knippenberg, 2007), which deals with those ambiguous results by incorporating as well as integrating the social categorization and the information decision making perspectives. The model set an agenda for future research in work group diversity.