The aim of this special issue is to address the question of income inequality from two different angles: first, identifying what elements and trends in the world of work may have contributed to income inequality; second, tackling inequalities not only from the two extremes - the top and the bottom - but from the perspective of middle-income groups or what we generally categorise as the 'middle class'. Are increasing income inequalities and increased polarisation leading also to the erosion of the middle class? What are the main transformations in the world of work over the past 20 years that may have affected the middle class? And how did the financial and economic crisis affect the middle class? On this basis, what are the driving forces in the world of work that we should develop to limit and even reduce income inequalities in the future?