This document summarizes mobile activities among US teens based on a presentation to the ARF Council. It finds that the majority of teens are on family plans and have texting plans. Top mobile activities among teens include downloading songs, uploading photos, playing games, and using major IM services. While teens are avid online users, their mobile device capabilities are often limited, constraining activities like YouTube viewing. The iPhone is becoming a popular smartphone for teens and may boost mobile browsing and app usage. Teens prefer communication and personal media over reference on mobile.