HPV vaccination has the potential to dramatically reduce rates of cervical, oropharyngeal, vaginal, vulvar, anal, and penile cancers. However, HPV vaccination rates in the US lag behind other countries, and HPV vaccine has lower coverage than other adolescent vaccines. Initiation of the vaccine series at ages 9-10 has been suggested as a way to improve vaccination utilization and increase the number of adolescents who complete their series on time.