We estimate the distribution of life cycle wages for cohorts of prime-age men and women in the US. A quantile selection model is used to consistently recover the full distribution of wages accounting for systematic differences in employment, permitting us to construct gender and education-specific age-wage profiles, as well as measures of life cycle gender wage gaps. Although common within-group time effects are shown to be a key driver of labour-market inequalities across gender, important additional differences by birth cohort emerge with more recent cohorts of women delaying child rearing, and by implication the onset of child penalties in wages. These important cross-cohort differences help account for the stalling of progress in gender wage gaps over the past quarter century.