OBJECTIVETo describe the rate and timeliness of diagnostic resolution after an abnormal screening mammogram in the ACR's National Mammography Database.METHODSAbnormal screening mammograms (BI-RADS 0 assessment) in the National Mammography Database from January 1, 2008, to December 31, 2021, were retrospectively identified. The rates and timeliness of follow-up with diagnostic evaluation and biopsy were assessed and compared across patient and facility demographics.RESULTSAmong the 2,874,310 screening mammograms reported as abnormal, follow-up was documented in 66.4% (n = 1,909,326). Lower follow-up rates were observed in younger women (59.4% in women < 30 years, 63.2% in women 30-39 years), Black (57.4%) and American Indian (59.5%) women, and women with no breast cancer family history (63.0%). The overall median time to diagnostic evaluation was 9 days. Longer median diagnostic evaluation time was noted in Black (14 days), other or mixed race (14 days), and Hispanic women (13 days). Of the 318,977 recalled screening mammograms recommended for biopsy, 238,556 (74.8%) biopsies were documented. Lower biopsy rates were noted in older women (71.5% in women aged ≥80) and Black (71.5%) and American Indian (52.2%) women. The overall median time from diagnostic evaluation to biopsy was 21 days. Longer median biopsy time was noted in older (23 days aged ≥80), Black (25 days), mixed or other race (26 days), and Hispanic women (23 days), and rural (24 days) or community hospital affiliated facilities (22 days).DISCUSSIONThere is variability in the rates and timeliness of diagnostic evaluation and biopsy in women with abnormal screening mammogram. Subsets of women and facilities could benefit from targeted interventions to promote timely diagnostic resolution and biopsy after an abnormal screening mammogram.