The purpose of this study was to identify factors associated with diagnostic follow-up after an abnormal mammogram in a national sample of women in the U.S. The sample was selected from the year 2000 National Health Interview Survey and included 1901 women aged 30 and above who reported ever having an abnormal mammogram. The outcome measure was receipt of at least some diagnostic follow-up after an abnormal mammogram. Bivariate and multivariate logistic regression analyses were used to explore the associations between sociodemographic characteristics, general health and health behaviors, cancer risk and risk perceptions, and health care utilization characteristics and follow-up. Approximately 9% of women who reported ever having abnormal mammograms reported not completing any additional diagnostic follow-up. Controlling for all other factors, women with less than a high school education were less likely to report follow-up after an abnormal mammogram than were women who had at least completed college (odds ratio = 0.56; 95% confidence interval: 0.32, 0.98). Younger women and women in poorer health were also less likely to report follow-up. Women who perceived a high versus low level of cancer in their family were more likely to report follow-up (odds ratio = 1.65; 95% confidence interval: 1.04, 2.62), controlling for all other factors. In a national sample of women with abnormal mammograms, a substantial number did not complete any diagnostic follow-up, potentially reducing the effectiveness of mammography screening programs in the U.S. Additional research on subsequent screening behaviors for women with incomplete follow-up and in-depth exploration of the roles of patient-provider interactions and health care system factors related to the index abnormal mammogram is warranted.