Have our societies become more meritocratic, in the sense of more open , more fluid ? And if so, why, since when, and how quickly? We answer these points by studying intergenerational social mobility during the past 300 years. More precisely, we compare the social class positions of children with those of their parents in various epochs, countries, and within countries in various regions, and relate these associations to the institutional contexts of the societies and to notable characteristics of the individuals in question.Has there been a trend towards more intergenerational social mobility in all or some parts of Europe? Have levels of mobility converged? If so, where and when did those trends start? What were the determinants of social mobility in the various regions and historical periods? Which institutions have historically furthered and which have hampered social mobility between the generations?This research project is grounded in the belief that social mobility patterns differ significantly and meaningfully over time and between regions. This has been masked by the fact that even the most brilliant contemporary studies of social mobility (a) have only the short time span surveys allow, (b) can thus only partially consider institutional variation, and (c) assume invariance or linear trends. Historical variance often appears either absent or meaningless.The long time horizon of this research programme in combination with measured institutional variation at the regional level in historical societies will allow us to (a) capture slow changes, (b) test better for changes that are non-linear and do not appear in all regions at the same time, and (c) connect observed changes to institutional determinants.We will do this using a unique historical database of 3.7 million individual records from historical vital registers, employed in combination with surveys, autobiographies, job advertisements in newspapers, and data on institutional contexts. U