Context: Human papillomavirus (HPV) vaccine, licensed for use in 9--26-year-olds, is most effective when given before sexual activity begins. HPV causes genital warts, is associated with several cancers and disproportionately affects racial and ethnic minorities. Parents are typically unaware of male HPV vaccine; messages that might motivate them to get their preteenage sons vaccinated are unexplored. Methods: Messages promoting vaccination of preteenage boys were designed and tested in 2009 and 2010. Five focus groups were conducted with 29 black parents of 11-12-year-old boys, recruited through three churches and a middle school in North Carolina, and a racially diverse sample of 100 parents of 9-13-year-old boys in a university-based adolescent health clinic was interviewed. A constant comparison method was used to code transcripts and interpret themes. Chi-square and t tests or analyses of variance were used to assess differences in quantitative data. Results: Focus group parents knew little about HPV in males. Although concerned about safety and cost, parents supported vaccination for their sons. They wanted to see racial diversity and both parents in motivational materials. In interviews, 89% of parents reported never having heard of male HPV vaccine. The largest proportion said that a message stressing the prevalence and possible consequences of HPV infection was the most motivating (32%); the design favored by the largest proportion (43%) showed two parents. Conclusions: Messages that may most motivate parents to get preteenage boys vaccinated against HPV focus on infection risk and include images of parents with their sons. © 2012 by the Guttmacher Institute.