to construct 3 categories of mammogram history: (1) never had a mammogram, (2) had over a year ago, and (3) had less than a year ago. We tested for differences in importance evaluations by mammogram history using ordered logit regression. Analyses applied the GfK survey weights to adjust for nonresponse bias and panel nonresponse to produce nationally-representative estimates. The study was determined to be exempt from review by the University of Minnesota institutional review board.Results | Fifty-eight (14.2%) participants reported never having a mammogram, 197 (56.4%) reported having a mammogram within the past year, and 103 (29.4%) reported having a mammogram less recently. Nearly all respondents (366, >90% for each) were aware of 4 statements describing mammography benefits (Table 1). When asked to rate their importance, most (223 [54.8]) concluded that each benefit was "very important." Respondents' awareness of harms, however, was much more variable (Table 2). Although only 108 (26.5%) reported prior awareness of overdiagnosis and 161 (39.7%) of overtreatment, 305 (74.9%) were aware of false-positive results and the potential of psychological distress. In contrast to their evaluations of benefits, fewer women rated harms as very important, ranging from 61 (15.1%) (health care system costs) to 117 (28.7%) (overtreatment). There were no statistically significant differences in awareness or ratings of importance by age group (40-49 years vs 50-59 years).Women who reported having a mammogram within the past year were significantly more likely to rate all 4 benefits as very important, compared with those who who never had a mammogram (62.4%-74.9% vs 44.9%-58.0%; differences significant at P<.05). Women who reported having a mammogram within the past year were significantly less likely to rate health care system costs and radiation harms as very important compared with those who never had a mammogram (11.5% and 15.1% vs 22.9% and 25.7%; differences significant at P<.05).Discussion | Women are more aware of the benefits of mammography screening than the harms, and women who have recently undergone mammography are more likely to judge these benefits as important. This may be owing to a lack of balanced information from physicians, 5 public health officials, news media, and disease advocacy groups that have long emphasized screening's benefits. Our findings suggest that there are opportunities for targeted education and communication at both the general public and individual levels, with a focus on educating women on the harms of screening, which they are much more likely to experience than benefits. However, the fact that women are predisposed to consider benefits as more important than harms poses a challenge to informed decision making about screening, suggesting the need for new paradigms in communicating the cumulative risks of the benefits and harms.