A choice-format, conjoint-analysis survey was developed and fielded to estimate how features of human papillomavirus (HPV) vaccines affect mothers' perceived benefit and stated vaccine uptake for daughters. Data were collected from a national sample of 307 U.S. mothers of girls aged 13-17 years who had not yet received an HPV vaccine. Preferences for four features of HPV vaccines were evaluated: protection against cervical cancer, protection against genital warts, duration of protection, and cost. We estimate that mean maximum willingness-to-pay (WTP)-an economic measure of the total benefits to consumers-for current HPV vaccine technology ranges between $560 and $660. All vaccine features were statistically significant determinants of WTP and uptake. Mothers were willing to pay $238 more for a vaccine that provides 90% protection for genital warts relative to a vaccine that provides no protection against warts. WTP for lifetime protection vs. 10 years protection was $245. Mothers strongly valued greater cervical cancer efficacy, with 100% protection against cervical cancers the most desired feature overall. Adding a second HPV vaccine choice to U.S. consumers' alternatives is predicted to increase stated uptake by 16%. Several features were significantly associated with stated choices and uptake: age of mother, race/ethnicity, household income, and concern about HPV risks. These findings provide new data on how HPV vaccines are viewed and valued by mothers, and how uptake may change in the context of evolving vaccine technology and as new data are reported on duration and efficacy.