We employ newly developed methods to disentangle age, period and cohort effects on non-marital fertility ratios from 1972 through 2002 for black and white women ages 20-44 in the United States. We focus on three cohort factors: family structure, school enrollment and the sex ratio. For both blacks and whites, cohorts with less traditional family structures have higher NFRs. Other results differ by race. The impact of school enrollment on NFRs is significantly negative for whites, but significantly positive for blacks. The impact of sex ratio is significantly negative for blacks, but insignificant for whites. If black women and white women had cohort characteristics typical of the other group, age-specific NFRs for black women would decline markedly, while those for whites would increase markedly. (Contains 6 tables and 11 notes.)