An estimated 5% of human cancers are caused by human papillomavirus (HPV) infections, and most of these cancers are of the cervix. Two prophylactic HPV vaccines that target the two most oncogenic virus types, HPV16 and HPV18, are now commercially available. In controlled clinical trials, the vaccines proved to be effective at preventing incident anogenital infection and the associated neoplastic disease that is induced by these virus types. Here, we highlight the specific aspects of HPV biology and vaccine composition that are likely to contribute to the efficacy of these vaccines, and we discuss how these particular features might or might not be relevant for the development of effective vaccines against other sexually transmitted viruses such as HIV and herpes simplex virus (HSV).