This study tests a new way, called **TweenVax**, to promote the HPV vaccine for kids aged 9-12. The **HPV vaccine** helps prevent certain types of cancers caused by the Human Papillomavirus. The **TweenVax** program aims to improve vaccination rates by offering more information and support to doctors, staff, parents, and kids. The study is comparing three different approaches: one group gets the full TweenVax program, another gets parts of it, and the last group continues with regular vaccination practices. The goal is to see if the TweenVax approach helps more kids finish their vaccinations by age 13. Doctors' offices taking part in the study will be followed for up to a year.

• The study lasts about 9 months, plus follow-up for a year.
• Participants are kids aged 9-12 who haven't started the HPV vaccine yet.
• Doctors' offices must have electronic records and see enough kids to join.