Leach, van Zomeren, Zebel, Vliek, Pennekamp, Doosje, Ouwerkerk, and Spears (2008) propose a hierarchical, multi-component model of in-group identification, consisting of five components: individual self-stereotyping, in-group homogeneity, satisfaction, solidarity, and centrality. These components are organized into two broader dimensions: group-level self-definition (individual self-stereotyping and in-group homogeneity) and self-investment (satisfaction, solidarity, and centrality). The study includes seven studies that validate the model through confirmatory factor analysis, construct validity, and predictive validity. The findings suggest that the hierarchical model provides a more comprehensive understanding of in-group identification than previous single-dimensional approaches. The model highlights the importance of both self-definition and self-investment in shaping individuals' identification with in-groups. The study also demonstrates that the five components are distinct and have unique relationships with established measures of in-group identification. The results support the conceptual and empirical value of the hierarchical model, which offers a more nuanced understanding of in-group identification. The model has implications for understanding intergroup dynamics and the psychological and social consequences of group membership.Leach, van Zomeren, Zebel, Vliek, Pennekamp, Doosje, Ouwerkerk, and Spears (2008) propose a hierarchical, multi-component model of in-group identification, consisting of five components: individual self-stereotyping, in-group homogeneity, satisfaction, solidarity, and centrality. These components are organized into two broader dimensions: group-level self-definition (individual self-stereotyping and in-group homogeneity) and self-investment (satisfaction, solidarity, and centrality). The study includes seven studies that validate the model through confirmatory factor analysis, construct validity, and predictive validity. The findings suggest that the hierarchical model provides a more comprehensive understanding of in-group identification than previous single-dimensional approaches. The model highlights the importance of both self-definition and self-investment in shaping individuals' identification with in-groups. The study also demonstrates that the five components are distinct and have unique relationships with established measures of in-group identification. The results support the conceptual and empirical value of the hierarchical model, which offers a more nuanced understanding of in-group identification. The model has implications for understanding intergroup dynamics and the psychological and social consequences of group membership.