ObjectivesIn recent years mindfulness has gone mainstream, reaching many adolescents through school programs and smartphone applications. Yet there is little empirical understanding of what mindfulness practice is like for adolescents. This qualitative study sought to capture adolescents’ lived experiences as they embarked on a period of intensive mindfulness practice.MethodsThis multi-method qualitative study involved 23 self-selected youth (Mage = 16.35 years, SD = 1.58, 57% girls, 52% White) who participated in a six-day residential mindfulness retreat. Participants wrote reflections about their mindfulness practice each night of the retreat and discussed their experiences in focus groups immediately after the retreat. Data were analyzed using a two-cycle coding process to categorize common patterns of adolescents’ experiences into conceptually meaningful categories. ResultsAdolescents reported an array of experiences of distress from cognitive (83% of adolescents; e.g., self-loathing and rumination), to emotional (87% of adolescents; e.g., sadness), to physical distress (44% of adolescents; e.g., physical pain) during mindfulness training. They also described a range of well-being experiences from cognitive (87% of adolescents; e.g., self-inquiry and discovery), to emotional (65% of adolescents; e.g., acceptance), to social well-being (39% of adolescents; e.g., loving-kindness and connection). Experiences of distress and well-being were relatively balanced overall, yet girls and experienced meditators reported greater distress.ConclusionsThis study paints a descriptive picture of adolescents’ experiences during mindfulness practice and suggests that their experiences during mindfulness might reflect core developmental concerns. Implications for developmental science and adolescent-informed mindfulness training programs are discussed.