A wealth of literature has examined the association between breastfeeding and the development of cognitive abilities in childhood. In particular, at least some evidence exists suggesting that breastfed children perform better on measures of intelligence later in life. Although a correlation appears to be present, fewer observational studies have included appropriate adjustment for potentially confounding variables; maternal intelligence, maternal education, and cognitive stimulation provided by mothers being chief among them. As a result, we analyze a national sample of approximately 790 American respondents to test the association between breastfeeding and intelligence during childhood and adolescence using multiple intelligence tests and controlling for a range of key covariates. Our results suggest that the correlation between breastfeeding throughout the first six months of life and intelligence is statistically significant and consistent, yet of substantively minor impact.