At the very end of the 1990s a number of social psychologists started to draw on and extend social identity theorizing to understand leadership as a social influence process grounded in a sense of shared group membership – one in which people’s potential to lead rests on the extent to which they are perceived by followers to embody the group’s identity. Such individuals are trusted by the group and thus able to define the group’s identity, and to motivate followers to place the group’s collective interest above their own personal self-interest and to hence act in group ways that attempt to take the group forward. One of the first theoretical statements (Hogg, 2001) was quickly followed by early extensions, refinements, and empirical reviews (e.g., Ellemers, de Gilder, & Haslam, 2004; Hogg & Van Knippenberg, 2003; Van Knippenberg & Hogg, 2003a; Van Knippenberg, Van Knippenberg, De Cremer, & Hogg, 2004; Reicher, Haslam, & Hopkins, 2005). There was also an edited book (Van Knippenberg & Hogg, 2003b), and in 2005 a special issue of The Leadership Quarterly (Van Knippenberg, Van Knippenberg, De Cremer, & Hogg, 2005).