Since 1980, the average age of working registered nurses (RNs) has increased by over four years, and the number of RNs under age 30 has declined sharply. This rapid aging of the RN workforce has been attributed in part to the increasing number of RNs who take degrees from two-year associate programs instead of four-year baccalaureate programs. In this second of a four-part series on changes in the RN workforce, David Auerbach, Peter Buerhaus and Douglas Staiger examine the interplay between the increasing number of RNs graduating from associate programs and the aging of the RN workforce. Indeed, the expansion of associate degree programs has made it possible for women in mid or late career to decide to become RNs, which contributes to the increasing average age of the RN workforce. However, these researchers find that the more likely underlying cause for the increasing average age of the nursing workforce is the large cohort of women born during the baby boom years who would eventually become RNs. Another contributing factor to the rise in the average age of the RN workforce is that baccalaureate nursing programs are having difficulty attracting large enough groups of young people to offset the trend. The authors used data from the National Sample Survey of Registered Nurses (NSSRNs), a survey conducted every four years and widely recognized as the principle sources of demographic, employment, and educational information about RNs in the United States. The next article in this series examines the effects of expanding career opportunities for women on the RN workforce.