The American Society for Colposcopy and Cervical Pathology (ASCCP) National Consensus Conference for the Management of Women With Cervical Cytological Abnormalities and Cervical Cancer Precursors was held on the National Institutes of Health campus in Bethesda, Md, September 6-8, 2001. The conference was attended by 121 representatives from 29 national organizations interested in cervical cancer screening issues. For the first time, guidelines for the management of women with abnormal cervical cytology, developed from evidence-based literature, were presented to delegates from the majority of organizations with interest in cervical cancer screening, voted on, and revised when necessary to achieve a majority two-thirds approval. This development of consensus-approved guidelines is likely to be considered one of the most important milestones to date in the management of women with abnormal cervical cytology. The timing of this Consensus Conference resulted from the convergence of many different factors, including new cytologic terminology developed at the Bethesda 2001 workshop and publication of the enrollment data from the National Cancer Institute's Atypical Squamous Cells of Undetermined Significance (ASC-US)/Low-Grade Squamous Intraepithelial Lesions (LSIL) Triage Study, otherwise known as ALTS. Additionally, new preliminary longitudinal ALTS data provided much of the information on the natural history of abnormal Papanicolaou tests and cervical intraepithelial neoplasia (CIN), as well as data on the performance of both new liquid-based cytology and human papillomavirus (HPV) DNA testing in the management of women following colposcopy. The result was a large database of new information that provided the foundation for the ASCCP Consensus Conference. This article covers only the recommendations of the ASCCP Guidelines that were based in large part on the results of the ALTS trial. Therefore, the focus is on the management of women with equivocal (ASC-US) and low-grade (LSIL) cytologic abnormalities. Management of women with these cytologic abnormalities has been particularly problematic, because individually these women are at least risk for CIN 3 and cancer, yet their sheer numerical dominance ensures that they account for the majority of high-grade CIN detected in the United States in the follow-up of abnormal cervical cytology. Data from ALTS confirmed that women with ASC-US could be safely managed by any of the conventional approaches (repeat Papanicolaou test, immediate colposcopy, or HPV testing), but that the preferred management approach for women having an ASC-US report from liquid-based cytology was to assess the patient's risk by testing for HPV. Additionally, longitudinal ALTS data determined that repeat liquid-based cytology at 6 and 12 months and an HPV test at 12 months were nearly equivalent options in the follow-up of women referred for HPV-positive ASC or LSIL, yet not found to have CIN 2+ at initial colposcopy. Therefore, all follow-up recommendations for women with CIN 1 or lower postcolposcopy findings include these 2 options. The data and the recommendations for the management of ASC-US, ASC cannot exclude high-grade squamous intraepithelial lesion, and LSIL are discussed.