Pickett came to international prominence with a book she wrote with Richard Wilkinson in 2009, The Spirit Level. That book used a battery of facts to argue that countries with the greatest overall inequality – even those that seemed to be richest – had the worst levels of health, social cohesion and human capital development. The Spirit Level sold more than 300,000 copies, was translated into 26 languages and was named by the Guardian as one of the 100 most influential books of the 21st century. Pickett and Wilkinson followed it, in 2018, with The Inner Level, which set out to illustrate the many ways in which the chronic stress caused by high inequality negatively affects our psychological wellbeing.