This paper provides an argument in favour of federal institutional design on the basis that it is more congenial to the preservation and promotion of normatively desirable societal diversity than its unitary alternative. Seeking inspiration in the work of three of the most influential liberal thinkers of the nineteenth century: John Stuart Mill; Alexis de Tocqueville; and Lord Acton, I construct a novel case for federalism that focuses on the inherent benefits of a dual/multi-layered governmental structure. Section one argues for (...) the value of diversity, stating that it can both improve the authenticity of individually exercised autonomy, and improve the quality of individually espoused moral views. Section two considers the potential dangers posed by the unitary state to the flourishing of diversity through the centralisation of key institutions. Section three shows how the federal model sidesteps these pitfalls, and offers a more auspicious environment for the cultivation and enjoyment of diversity. (shrink)