PURPOSE Data confirm that high rates of human papillomavirus (HPV) vaccination have not been achieved despite strong clinician endorsement of the vaccine. We conducted a study of primary care clinicians to assess the broad range of health care delivery, health policy, and attitudinal factors influencing vaccination uptake and opportunities for informed decision making. METHODSWe implemented a mixed methods study in RIOS Net, a primary care practice-based research network in New Mexico. We first conducted qualitative, in-depth interviews with primary care clinicians, health policy makers, and immunization experts, and followed up with a confirmatory survey distributed to RIOS Net clinician members. RESULTSHealth service delivery challenges emerged as the greatest barrier to HPV vaccination, specifically the lack of capacity to track and distribute reminders to eligible patients. Clinicians also reported variations in counseling approaches attributable to both age and emphasis on the cancer prevention benefits of the vaccine. There was no evidence of sociocultural influences on vaccine decision making, nor did concerns about perceived overprotection emerge.CONCLUSIONS Our findings, based on a long-term program of research, suggest that both patients' attributes and health system delivery are most influential in HPV vaccination coverage challenges. Interventions targeting innovative communication techniques, as well as health system changes that build on efforts toward coordinated care and utilization of other venues to promote vaccination, will be necessary to address these challenges. Control and Prevention (CDC) reports that the human papillomavirus (HPV) vaccine rates trail those of other vaccines for teenagers: tetanus, diphtheria, and pertussis (Tdap), and menningitis. INTRODUCTION T he Centers for Disease1 Nationally, 57.3% reported getting the first dose of HPV in 2013, a modest increase from 2012 rates (53.8%). Full coverage (not considering the time frame in which the doses were given) is also less than ideal: among girls aged 13 to 17 years, 37.6% received all 3 doses. National HPV vaccination data for younger eligible recipients (eg, aged 9 to 12 years) are not provided by the CDC. Given new challenges in the health service delivery environment, 3 innovative approaches for increasing HPV vaccination coverage are needed.In the period before the vaccine's release, research was aimed at understanding factors that might predict vaccination uptake. Although identification of such factors varied, there was strong consensus that primary care clinicians would play an important role in HPV vaccine dissemination. [4][5][6] During the prelicensure period, we conducted a qualitative study in primary care settings to better understand and anticipate the challenges and opportunities for HPV vaccination. In this journal, we reported the 4 major domains that emerged from our research, which included (1) the complexity of HPV counseling in the clinical encounter, (2) the recom- 355mended age, (3) system/compl...