In this study we evaluated CDP: EWC, a large public health screening program for low-income women to determine whether the ASC-H term, introduced in the 2001 revision to the Bethesda System, has facilitated the detection of the most serious precancerous cervical lesions such as CIN-II-III/CIS, including accuracy of detection and minimizing diagnostic delays. Pap test and biopsy data from the period 2003-2006 were compared with those from 1995-1999, and included analysis of a subset of rarely and never-screened for each study period. More ASC-H Pap tests were followed by CIN-II+ biopsies (20%) than ASCUS Pap tests (5%). Thirteen percent of ASC-H showed CIN-III/CIS on follow-up biopsy. Following the introduction of ASC-H, negative and LSIL Pap tests followed by CIN-III/CIS biopsies decreased from 5.6% to 0.37% and 9.2% to 4.4%, respectively. Fewer CIN-III/CIS cases were preceded by Pap tests with negative and ASCUS results in 2003-2005 as compared with 1995-1999. The number of days from screening to diagnosis for women aged 25-39 years with ASC-H Pap test results (58 days) was less than for ASCUS results (78 days) for the current study period. In this high-risk multi-ethnic population, ASC-H more effectively communicates equivocal findings likely to represent HSIL leading to more rapid follow-up. The incidence of CIN-II or CIN-III/CIS following ASC-H Pap tests is lower than generally appreciated for this population, including for rarely or never-screened high-risk women. Fewer CIN-III/CIS lesions were detected following negative and ASCUS Pap results. Compliance with follow-up is less than ideal for this population.