A staggering rise in wealth disparity has transformed New Zealand from one of the developed world's most equal nations to one of the most unequal. International bestseller The Spirit Level argued in 2009 that income inequality is the biggest single cause of a huge range of social problems. In contrast, more equal societies are consistently the healthiest, best educated and most free of crime. Inequality addresses these questions in the New Zealand context - a powerful argument from some of the country's leading commentators.