Asthma apps often lack strong theoretical underpinnings. We describe how specific features of asthma apps influenced adolescents' self-observation, self-judgment, and self-reactions, which are key constructs of Self-Regulation Theory (SRT). Adolescents (ages 12-16) with persistent asthma (n = 20) used two asthma self-management apps over a 1-week period. During semi-structured interviews, participants identified their asthma goals and the app features that best promoted self-observation, self-judgment, and fostered positive self-reactions. Interviews were digitally recorded, transcribed verbatim, and analyzed thematically using MAXQDA. Adolescents' goals were to reduce the impact of asthma on their lives. Adolescents reported that self-check quizzes, reminders, and charting features increased their ability to self-observe and self-judge their asthma, which, in turn, helped them feel more confident they could manage their asthma independently and keep their asthma well-controlled. Asthma apps can positively influence adolescents' self-management behaviors via increased self-observation, self-judgment, and increased self-efficacy.