This chapter summarises the research on intergenerational social class mobility. The chapter begins with a brief history of sociological research on occupational mobility. It then discusses conceptual issues related, first, to the classification of occupations into classes or hierarchies, and second, to the distinction between absolute and relative mobility. Some of the major theories, research findings and controversies with respect to comparative research on occupational mobility are then reviewed as well as trends over time. The chapter concludes with a brief discussion of priorities for future research, including more within-country studies that aim to uncover underlying mechanisms.