Guided by Social Learning Theory, competing hypotheses tested whether personal, environmental, or behavioral factors influenced gender differences in hand washing. A total of 170 observations were made in public restrooms on a university campus. Results suggested that differentiating patron use of urinals and commodes was appropriate for examining hand-washing differences between women and men. The research found hand-washing rates of men and women were similar if both had just used a commode. In contrast, after using urinals, men’s hand-washing rates were substantially lower than commode users. Although environmental factors appear to have an overriding influence over men’s hand washing, duration data suggest that the specific behavior performed in a restroom (e.g., urination or defecation) was a better predictor of hand-washing rates and durations. These findings contradict gender-socialization theory as the explanation for differences in hand washing and warrant further investigation of environmental and behavioral influences.