1. Introduction Matthew D. Adler and Ole F. Norheim; 2. Theory of prioritarianism Matthew D. Adler; 3. Well-being measurement Matthew D. Adler and Koen Decancq; 4. Prioritarianism and optimal taxation Matti Tuomala and Matthew Weinzierl; 5. Prioritarianism and measuring social progress Koen Decancq and Eric Schokkaert; 6. Prioritarianism and health policy Richard Cookson, Ole F. Norheim, and Ieva Skarda; 7. Prioritarianism and fatality risk regulation James K. Hammitt and Nicolas Treich; 8. Prioritarianism and climate change Maddalena Ferranna and Marc Fleurbaey; 9. Prioritarianism and education Erwin Ooghe; 10. Empirical research on ethical preferences: How popular is prioritarianism? Erik Schokkaert and Benoît Tarroux; 11. Prioritarianism and equality of opportunity Paolo Brunori, Francisco H.G. Ferreira, and Vito Peragine; 12. Prioritarianism and the covid-19 pandemic David E. Bloom, Maddalena Ferranna, and J. P. Sevilla.