In Oregon, as in other areas of the United States, a greater percentage of men than women bicycle. This study illuminates the gender gap in bicycling by exploring differences in bicycling between women and men in Oregon. A one-day statewide travel survey of more than 30,000 adults was examined. Comparisons between individual, household, and trip and activity characteristics for people grouped by gender (women versus men) and bicycling (made a bicycle trip or normally commuted by bicycle versus did not bicycle) were assessed using chi-square tests of independence. Many significant differences were found. In particular, women who lived alone, were not working, had no high school degree or drivers license, and lived in low-income households or zero-vehicle households were less likely to bicycle than other women. Men with similar characteristics did not exhibit the same trends; sometimes they were even more likely to bicycle. These findings are consistent with a perspective that women who bicycle are more likely to bicycle by choice, whereas women of fewer means are less likely to turn to bicycling than are their male counterparts. In addition, there was partial support for the idea that womens roles and responsibilities may contribute to this deficit (that is, for household maintenance and escorting but not necessarily for the presence of children). The studys results begin to suggest a rethinking of bicycle-promoting policies and interventions to target certain women better, although further research is needed to understand bicyclings gender gap more fully.