Pregnancy, birth, and the postpartum period are important events in the reproductive lives of women. Exercise guidelines exist for pregnancy, but recommendations for exercise during the postpartum period are virtually nonexistent. It is important to examine the theoretic concerns and potential benefits of exercise during this period, especially with respect to weight retention following pregnancy, lactation performance, and infant growth. It is recommended to increase the definition of the postpartum period to 1 year, because many physiologic changes due to pregnancy remain up to 1 year after delivery. Evidence-based guidelines are presented for postpartum exercise and lactation. Future research should address the impact of exercise and lactation on bone mineral density, nutrition status and weight loss, cardiovascular health, and how to optimize health promotion during the postpartum period.