_On Social Closure_ reinvigorates the idea of social closure as a basic sociological concept for understanding the strategies powerful groups use to improve their life chances at the expense of the less powerful. Jürgen Mackert provides sociological tools for analysing three critical forms of closure in the world today: exclusion in the context of neoliberalism; exploitation within global capitalism; and elimination in the ongoing legacy of settler colonialism, thereby transcending Eurocentric analyses. Mackert puts forward a mechanism-based explanatory approach identifies two critical social mechanisms that operate in various kinds of social closure struggles. The first explains how human beings, social groups, or communities are denied access to resources, rights, or critical networks, while the second explains how the powerful exert control that leaves the less powerful vulnerable and unable to fight back. Through a critical reconsideration and revision of existing concepts and by bringing in new ones, Jürgen Mackert develops a novel theoretical approach to social closure.