BACKGROUND AND PURPOSE Parity appears to be associated with carotid atherosclerosis in women aged 45 years and older. Studying this association among younger women and men may provide insight into whether this association relates predominantly to childbearing or child-rearing. METHODS The association between parity and carotid atherosclerosis (intima-media thickness and presence of plaques) was assessed in a cohort consisting of 750 women and 1164 men, all with at least one traditional cardiovascular risk factor, aged 18 to 80 years of age. Traditional cardiovascular risk factors were also assessed, and the Framingham Risk Score calculated. RESULTS In age-adjusted analyses, the number of children was associated with adiposity, fasting glucose, 2-hour glucose, Framingham risk score, and carotid atherosclerosis in women, but not in men. Multivariate linear regression models indicate that the prevalence of plaques was increased by 15% (95% CI, 2 to 29) per child among women, and 0% (95% CI, -10 to 11) among men, after adjustment for age, socioeconomic and lifestyle factors (including waist circumference). The association between parity and carotid intima-media thickness was similar in younger and older women (P(Heterogeneity)=0.20). CONCLUSIONS A higher number of children is associated with increased carotid atherosclerosis in both younger and older women, but not among men. These findings indicate that childbearing, but not child-rearing, may be a risk factor for atherosclerosis, and suggest the potential importance of considering the number of children when assessing the level of cardiovascular risk in women.