Used the experience sampling method to examine the psychological experiences of Italian adolescents in different leisure activities and their relationship to adolescent development. Found that structured activities, such as sports, hobbies, and reading related to high involvement, challenge, and experience of skills. Unstructured or relaxed leisure was associated with lower mood, lack of meaning, and disengagement. Concluded that the Aristotelian ideal of reflective leisure is rare among modern adolescents. (KB)