ABSTRACT Drawing from the implicit theories framework of Dweck (1986), we propose a new construct called Group Entity Belief (GEB), which is an individual difference construct reflecting the extent to which social identities are perceived as fixed and lasting aspects of the self. In this research, we tested the overarching hypothesis that high GEB is associated with stronger social identity effects. First, we examined the relationships between GEB and classic group-related variables such as collective self-esteem, commitment, and social identification. Second, we tested how much GEB predicts group-related outcome variables. Finally, we examined how GEB is associated with variables pertaining to past in-groups. These findings provide valuable insights into the psychological nature of GEB.