We examine trends in intergenerational educational mobility over the 20th century
in Denmark. We demonstrate how major compulsory schooling reforms substantially increased not only levels of education but also intergenerational mobility in education for children born in the 1940s through 1960s. For children born in the 1970s and 1980s, however, even as college education has expanded significantly, educational mobility has been declining. We empirically test different mechanisms that may account for this decline.