Why would one willingly fight for a foreign ruler? And why would foreign rulers recruit soldiers only from small minorities? In Military Clubs, Charles Miller argues these puzzles have a rational answer. He explains how rulers seek to hire from specific cultural and religious minorities – or 'Military Clubs' – which are best able to commit to a long run deal with the ruler to provide soldiers in return for collective economic, social and political benefits. Uncovering the rationality behind seemingly irrational behavior, he argues that rulers preferred groups which were best able to police their members against defecting from this deal. Comparing the historical experience of European colonial powers with failed attempts to build reliable military institutions in contemporary developing countries, Miller explores the tradeoff between the competing ethical imperatives of building a diverse and representative organization on the one hand and building an effective one on the other.