Objectives. To test whether paid family leave policies in California and New Jersey improved breastfeeding practices, overall and among key subgroups.Methods. We conducted difference-in-differences analyses, comparing pre-post policy changes in California and New Jersey with changes in states where no paid family leave policies were implemented. We examined a large, diverse sample of children born during 2001 to 2013 (n = 306 266), drawn from the 2003 to 2015 National Immunization Survey waves. Outcomes included ever breastfed, breastfed exclusively at 3 and 6 months, and still breastfed at 6 and 12 months, as well as duration of any breastfeeding and exclusive breastfeeding. We examined heterogeneity in policy response by maternal characteristics.Results. Paid family leave policies resulted in a modestly greater likelihood of exclusively breastfeeding at 6 months. Subgroup analyses were mixed, although several breastfeeding outcomes were consistently improved among married, White, higher-income, and older mothers.Conclusions. Exclusive breastfeeding improved after implementation of paid family leave policies in the overall sample, and additional benefits were noted for more advantaged mothers. This contributes critical evidence to an ongoing policy discussion, suggesting that subsequent paid family leave policies should be designed to target more vulnerable mothers.