Using data from a large household survey representative of the UK population, we studied how closely parents and adult children live to each other. We show that residential mobility over the life course tends to increase with the physical distance between the homes of parent and child. There are large differences in intergenerational proximity between the foreign-born and UK-born, and between ethnic groups. The determinants of intergenerational proximity from the parent's viewpoint are not identical to those from the child's viewpoint. Contrary to the findings of some earlier studies, intergenerational proximity, from the child's viewpoint, does not vary with the number of siblings. But from the parent's viewpoint, having more children is unambiguously associated with a higher probability of living close to at least one child. We end with a brief discussion of some possible implications of several long-term demographic trends in the UK for intergenerational proximity.