The objective of this article is to study a barrier for breastfeeding women working full-time outside the home: breast milk expression in the workplace. Data are from a large corporation that provides employee benefits. Mothers express breast milk about twice a day when infants are 4 months old (x = 2.2 +/- 0.8) and 6 months old (x = 1.9 +/- 0.6), with a significant decline in frequency (P <.05) comparing the 2 age groups. Most mothers spend 1 hour or less expressing breast milk when infants are 3 (82%) or 6 months old (96%), with a significant difference (P <.05) between the 2 age groups. Mothers of younger infants were no more likely to work fewer days per week than were mothers of older infants. Most women can express breast milk for 3- and 6-month-old infants in less than an hour, distributed in about 2 separate portions, in an employment environment supportive of breastfeeding.