Breastfeeding rates in the United States are suboptimal despite public health recommendations that infants are fed breastmilk for their first year of life. This study aimed to characterize the influence of social determinants of health on intended breastfeeding duration. This case-control study analyzed breastfeeding intent in 421 postpartum women. Data on social determinants and medical history were obtained from medical records and participant self-report. Logistic regression estimated the influence of demographic factors and social determinants on intent to breastfeed for durations of <6 months, 6-12 months, and at least 1 year. Thirty-five percent of mothers intended to breastfeed for at least 6 months, and 15% for 1 year. Social determinants that negatively predicted breastfeeding intent included not owning transportation and living in a dangerous neighborhood (p < 0.05). Women were more likely to intend to breastfeed for 12 months if they had knowledge of breastfeeding recommendations (adjusted odds ratio [aOR] 6.19, 95% confidence interval [CI 2.67-14.34]), an identifiable medical provider (aOR 2.64 [CI 1.22-5.72]), familial support (aOR 2.80 [CI 1.01-7.80]), or were married (aOR 2.55 [CI 1.01-6.46]). Sociodemographic factors that negatively influenced breastfeeding intent included non-Hispanic Black race, no high school diploma, cigarette use, income below $20,000, fewer than five prenatal visits, and WIC or Medicaid enrollment (p < 0.05). Women who lack familial support, an identifiable healthcare provider, or knowledge of breastfeeding guidelines are less likely to intend to breastfeed. Public health initiatives should address these determinants to improve breastfeeding and infant outcomes.