OBJECTIVES: The aims of this study were to examine mothers' intention to vaccinate their daughters and themselves against human papillomavirus and to determine which demographic, behavioral, and attitudinal factors were associated with intention to vaccinate daughters. METHODS: We surveyed 10,521 US mothers, all nurses, between June 2006 and February 2007. Multivariable logistic regression models were used to determine which of the following factors were associated with a mother's intention to vaccinate a 9- to 12-year-old daughter: demographic factors, gynecologic history, belief that one's daughter should have regular Papanicolaou testing, beliefs about Papanicolaou testing outcomes (3-item scale), and beliefs about human papillomavirus vaccines (7-item scale measuring beliefs about human papillomavirus vaccine efficacy, impact of vaccination on sexual and Papanicolaou screening behaviors, severity of and susceptibility to human papillomavirus, and anticipated clinician recommendations). RESULTS: Of the 8832 mothers who completed a survey (84% response rate), 7207 had a daughter. Among mothers with a daughter, 48% intended to vaccinate a daughter if she were 9 to 12 years of age, 68% if she were 13 to 15 years of age, and 86% if she were 16 to 18 years of age. Forty-eight percent intended to receive the vaccine themselves if recommended. In multivariable regression models, variables significantly associated with intention to vaccinate a 9- to 12-year-old daughter included belief that one's daughter should have regular Papanicolaou testing and beliefs about human papillomavirus vaccines. CONCLUSIONS: In this first national study of mothers' attitudes about human papillomavirus vaccines, mothers' intention to vaccinate a daughter <13 years of age was lower than intention to vaccinate an older daughter, contrasting with national recommendations to target 11- to 12-year-old girls for vaccination. Educational interventions designed to affect mothers' willingness to vaccinate daughters should focus on human papillomavirus vaccine efficacy, behavioral impact of vaccination, perceived risk of human papillomavirus, and clinician support for vaccination.