The process of cervical carcinogenesis may take between 10 and 30 years from HPV infection to progression to invasive cancer, and many HPV infections never cause cancer. Thus, it is unclear if cervical cancer represents a threat to older women who face competing causes of mortality, if benefits outweigh harms in this group, and if screening into older age is a reasonable expenditure. Conducting a randomized trial to evaluate the effects of screening older women would not be feasible given the relative rarity of cervical cancer, the length of follow-up needed, and the large sample size required. In this situation, mathematical modeling can simulate population harms, benefits, and costs, and can guide policy decisions. A validated model shows that extending biennial screening with Pap smears and HPV testing from age 65 years to age 75 years would entail an additional 400 000 false-positive results. Biennial screening with Pap smears and for HPV between the ages of 20 and 65 years captures 86.6% of the benefits of lifetime