Introduction: In the U.S. HPV vaccination of adolescent males remains low, despite the recommendation for routine vaccination. Although research has highlighted that health care provider (HCP) recommendation is very influential in HPV vaccine uptake, research on this topic in the male population is lacking. Accordingly, we used a qualitative approach to identify HCP knowledge, attitudes, and behaviors regarding adolescent male HPV vaccination, one year after routine vaccination of adolescent males was recommended. Method: Twenty U.S. pediatric HCPs participated in 20-30 minute interviews about knowledge, attitudes, and practices regarding male HPV vaccination. Interviews were audiorecorded, transcribed and analyzed using inductive content analysis. Results: The providers had been in practice for 1-35 years, 75% were female, and 75% were White. Opinions on HPV vaccination were shaped by knowledge/perception of the risks and benefits of vaccination. Although all providers frequently offered HPV vaccine to male patients, the strength and content of the offer varied greatly.Vaccination opinions determined what issues were emphasized in the vaccine offer (e.g., stressing herd immunity, discussing prevention of genital warts), while adolescent age influenced if and how they pitched their vaccine offer (e.g., HPV as an STI). Most providers agreed with the ACIP recommendations, however, several expressed that providers' pre-existing opinions might remain unchanged despite the recommendations. Consistent with the literature on determinants of HPV vaccination, providers believed that their own recommendation was a major factor in a family's decision to vaccinate. Barriers to vaccination included the "newness" and sexual nature of the vaccine, lack of insurance coverage and the vaccine not being mandated. Conclusions: Providers' opinions about, and approaches to offering, HPV vaccination to males were highly variable. Interventions designed to improve male HPV vaccination 3 should focus on helping providers to routinely recommend the vaccine to all of their eligible patients, both males and females.