This is a retrospective cohort study based on a health claims database, the Truven Commercial Claims and Encounters (CCAE) database. Participants will enter the cohort when, after using Concerta continuously for at least 60 days after October 3, 2012, they receive a dispensing of the AG or EG formulation within 15 days of the end of the days of Concerta supplied. The date of that dispensing of the AG or EG formulation is the participants index date. This study will track various events, example, back-switches, and methylphenidate dose changes over time (the 60 days before the switch from Concerta to an AG or EG generic compared to the 60 days after that switch).