We have made dramatic changes in the nutrition and management of dairy heifers over the past 20 years. Significant basic nutrition research and applied management studies have moved our knowledge of the dairy heifer forward. Increasingly, the industry has become more progressive in adopting management practices based on the physiology and nutrient needs of the heifer. The US has experienced consistent progress toward optimizing heifer growth rates and reducing age at first calving. Part of this change has to be a result of economic analyses showing that age at first calving drives the overall cost of the heifer enterprise. Studies using data from the early 1990s demonstrated the economic advantage of calving at 23 to 24 mo, yet the industry lagged far behind at that time. Recent industry trends show a marked reduction in age at first calving, from 28 mo in 1980 to 25.5 mo in 2004 and a sustained decline since then. Research into growth rates and standards for body size and stature have been instrumental in developing rearing programs that provide heifers with adequate nutrients to support growth and improve milk production in first lactation. Free stall and bedded pack housing along with use of higher quality forage in total mixed rations and limit feeding systems have improved the feed efficiency of heifers to allow improved growth rates and breeding at younger ages. Transitioning the weaned heifer to this feed efficient system remains a problem on many farms. There remains opportunity for research to more fully understand management and feed efficiency of heifers as they continue to mature at younger ages. Currently, calving at 22 to 23 mo appears to best balance the cost of growing heifers with their lifetime production and income potential.