Marriage market estimates by sex and age are made for the US and England and Wales in 1990-91, using explicit data on age preferences. Availability is strongly differentiated by age and sex; it decreases with age for women, while the opposite is true for men. Decomposition shows that young women are advantaged largely by age preferences while older men are advantaged by population age-sex and marital status structure. Most men marry at ages when partners are in short supply, a finding that is examined in detail. Implications for gender power relations through the life course are considered.