This research brief examines changes in the age distribution of faculty in the University of Wisconsin (UW) system over time and trends in faculty retirement. Findings indicate that: (1) in 1997-98, 35 percent of faculty were age 55 and older, 51 percent were between 40 and 54, and fewer than 15 percent were under 40; (2) on average, faculty at the UW comprehensive institutions were somewhat older than faculty at UW-Madison and UW-Milwaukee; faculty at the UW colleges were older than faculty in other system institutions; (3) faculty age distribution varied across academic disciplines, with engineering and physical sciences having both the highest percentage in the 55 and older age group and the highest percentage of faculty under 40; (4) between 1985-86 and 1997-98 the total number of UW system faculty declined by 9.8 percent; however, the number of faculty 55 and over increased by 18 percent and the number under age 40 declined by 41.4 percent, which changed the age distribution. Based on historical retirement rates, it is projected that 2,384 faculty members (close to 40 percent) systemwide will retire over the next decade. Text, figures, and graphs present the detailed analysis. Appendices include technical notes, additional tables, and notes on the projection methodology used. (DB)