Approximately 85% of mothers have expressed milk sometime since their infant was born. About 5.6% of these mothers exclusively pump their milk. There are many reasons for this and a number of unanswered questions regarding the practice–do the same health advantages accrue to the exclusively pumping mother compared with a parent that directly breastfeeds (reduction in reproductive cancers, type II diabetes, myocardial infarction, metabolic syndrome)? Are there different health outcomes for the infant? Is pumped milk equivalent to milk directly fed from the breast? Expressed milk can be exposed to nutrient degradation through handling, storing, and even altered depending on which bottle-feeding system is used. Bacterial richness is lower in pumped milk which can alter the infant gut microbiome. Milk lypolysis can occur during storage causing an off odor and rancid flavor. Breastmilk components communicate the time of day to infants through a process called chrononutrition and may not be circadian matched. Milk pumped during the day is different than milk pumped at night. This presentation will explore the many nuances of expressed breastmilk, breast pumps, pumping more effectively, typical problems and possible interventions. Recommendations will be provided for a healthy, successful experience.