This was a nurse-driven, hospital-based, prospective cohort study of data collected in 19 hospitals in San Bernardino and Riverside counties by California Perinatal Services Network on all mothers (n = 21 842) who delivered a singleton infant (37-40 weeks gestation) between July 2005 through June 2006. Multivariate ordinal logistic regression showed that maternal infant-feeding method intention (measured prior to birth), sociodemographic characteristics, intrapartum variables, and early skin-to-skin mother-infant contact during the first 3 hours following birth (controlling for delivery hospital) were correlated with exclusive breastfeeding during the maternity hospitalization. Compared with mothers with no early skin-to-skin contact, exclusive breastfeeding was higher in mothers who experienced skin-to-skin contact for 1 to 15 minutes (odds ratio [OR] 1.376; 95% confidence interval [CI], 1.189-1.593), 16 to 30 minutes (OR 1.665; 95% CI, 1.468-1.888), 31 to 59 minutes (OR 2.357; 95% CI, 2.061-2.695), and more than 1 hour (OR 3.145; 95% CI, 2.905-3.405). The results demonstrate a dose-response relationship between early skin-to-skin contact and breastfeeding exclusivity.