Of the military personnel serving in OEF and OIF, 89% are men and 11% women. Nearly all troops who served in Vietnam were men (only 7,494 women served) compared with over 200,000 women serving in OEF and OIF (Jacobs, 2000; Tanielian and Jaycox, 2008). Today’s service members are also somewhat older1 and more likely to be married than their Vietnam-era counterparts (Jacobs, 2000). The distribution of personnel ages varies among components of the military. According to the 2007 Demographics Report, over 40% of active-component officers are over 35 years old compared to 15% of active-component enlisted personnel (DOD, 2007). The numbers of active-component officers and enlisted members by age and service branch are summarized in Table 2.2. Members of the Marine Corps have the lowest average age, 25.0 years, and the Air Force has the highest, 29.6 years. The reserve-component officers and enlisted members are much older than the active-component officers and enlisted members, respectively (DOD, 2007). Among reserve-component officers, 73.6% are over 35 years old compared with 44.2% of active-component officers. Similarly, 55.3% of the reserve-component enlisted members are 30 years old or younger compared with 72.6% of the active-component enlisted members. Table 2.3 summarizes the numbers of reserve-component officers and enlisted personnel by age group and service branch.