A personal attitudes model (i.e., infant feeding choices are based on personal attitudes primarily) and a structural factors model (i.e., feeding choices are shaped by the structural contexts of women's lives, as much as personal attitudes) of women's breastfeeding behavior were tested by surveying a longitudinal sample of 548 mostly European American women recruited for the Wisconsin Maternity Leave and Health Project. Personal attitudes (enjoyment of breastfeeding, gender-role attitudes, and work and family salience) accounted for half as much variance in breastfeeding duration for women who were employed outside the home compared to those who were not. For women employed outside the home, both structural variables (length of maternity leave and workplace flexibility) and personal attitudes predicted duration. These results have implications for how we construct the issue of women's breastfeeding decisions.