Data from two British cohort studies show that women with children have lower wages than childless women. We develop an innovative decomposition of this 'family gap'. The crude pay gap between mothers and childless women in their thirties was similar in 1978 and 1991, but low pay in part-time work became more important in explaining this gap, and human capital less so. We find that, among full-time employees, women who broke their employment at childbirth were subsequently paid less than childless women. In contrast, mothers who maintained employment continuity were as well paid as childless women, but neither were as well remunerated as men.