Many who smoke in college do so infrequently and smoking conditions are not well understood. We examined smoking patterns among college fraternity and sorority members (N = 207) from a Midwestern university in three successive fall semesters in 2006-2008. Participants completed calendar-assisted retrospective assessments of 30-day smoking at up to five assessment points over 96 days. Overall smoking rates declined over the course of each semester and higher smoking on weekends was observed, with more variability among daily smokers. The most frequent categories of events to cue recall of smoking were socializing, work, and school. Findings can be used to target prevention efforts.