This chapter discusses the state of the intergenerational income mobility literature from the beginning of the 1990s, when new influential papers spurred the interest in studying this kind of mobility in a large number of countries. The academic interaction between this new literature and the more established class mobility approach in sociology is also discussed. In a concluding section of the chapter, two important tasks for future research are stressed. First, it is important to consider the specific concept of income used in the studies. Such concepts also change over time and from one generation to the next. Second, the relationship to the fundamental goal of equality of opportunity can be strengthened by considering the broader role of family and community background.