PIP: Urban, white, ever-married women, aged 15-44, were sampled in low and high income census tracts in 16 U.S. cities, using a short adaptation of the Peabody Picture Vocabulary Test as a measure of IQ. After analysis of covariance, in which IQ was the independent variable and children ever born (CEB) was the dependent variable, it was found that there is .19 difference between the mean CEB of high- and low-IQ groups when covariables are controlled. It was shown that there was no significant difference in desired family size associated with IQ. But since the low-IQ women have more fertility than high-IQ women, effectiveness of contraceptive methods was examined. Examination showed that lower fertility was achieved by more effective use by the high-IQ women of methods of theoretically similar effectiveness. Also, those women not using a physician administered contraceptive (PAC) in the 3-year study period had unwanted births at about 3 times the rate of those who used PAC for the entire period. Thus, all American women will have to learn to realize their own fertility goals.