This article is the first in a series examining the interplay between the aging of the nurse workforce and other factors driving the growing nursing shortage that are already affecting some specialty areas. Nearly 60% of the current RN workforce is over 40 years of age; and the percentage of RNs under age 30 has fallen by nearly 40% since 1980. The total number of FTE RNs is projected to shrink after 2010, likely resulting in shortages of RNs "when the large baby-boom generation of RNs starts to retire." Because ICUs have historically attracted younger RNs, the rapid decline in the number of RNs in the workforce under age 30 plays a large role in explaining the development of shortages in the ICU. The growing difficulties staffing operating rooms and other peri-operative services is seen as related to the aging work force as more diploma prepared nurses have been attracted to this specialty because they had educational exposure to this area.