More than 15 years ago, a relationship between human papillomavirus (HPV) infection and cervical cancer was recognized. Since then, important strides in understanding the virus have been made, particularly in the following areas: modes of transmission and risk factors associated with transmission; the oncogenic potential of specific viral types and the mechanism by which they cause cancer; and the spectrum of infection, ranging from asymptomatic carrier states to overt warts, preneoplastic lesions, and invasive cancer. Sophisticated new tests for the detection of HPV that hold great promise for improved screening for cervical cancer precursors and invasive cancer and for the triage of abnormal cervical cytology also have been developed. Understanding the immunology of HPV has allowed the development of new and more effective treatment modalities for HPV infection and the preliminary development of primary prevention modalities, including HPV vaccines.