Integrating positive variables into traditional models of youth mental health is important for building a more complete understanding of the factors implicated in both the absence of psychopathology as well as the presence of well-being. This dissertation aimed to explore how positive life events (PLEs) and positive cognition impact youth well-being, using a 5-day daily diary study, in which youth reported on their daily PLEs. A longitudinal model was employed to evaluate the impact of PLEs on longer-term well-being. In Chapter 1, the diary entries were qualitatively analyzed to evaluate the types of events youth typically experience and the qualities in PLEs that appear to facilitate positive experience. Youth were observed to report events involving a variety of people, across diverse locations and contexts. Life events that involved connection, laughter, play, kindness, creativity, relaxation, achievement, or simple pleasures appeared to contribute most to youth positive experience. Youth appeared to derive positive experiences from the simple events in their daily lives, and were observed to engage in positive emotion regulation, and experience upward spirals and a reparative impact of their daily PLEs. In Chapter 2, qualitative analyses highlighted processes that may interfere with youth PLEs. Analyses indicated that youth often integrate negative reflections when reporting on their PLEs. In Chapter 3, quantitative analyses were conducted to evaluate the implications of youth PLEs for their state and trait emotional well-being. Multilevel modeling indicated that greater objective and subjective PLEs, higher positive emotion regulation, and lower negative reactions to PLEs, all predicted increased positive affect. Furthermore, lower positive reactions to PLEs and higher negative reactions to PLEs predicted increased negative affect. In Chapter 4, the longer-term implications of PLEs for youth emotional development were evaluated. The results indicated that over time, lower positive schemas interact with subjective PLE intensity to predict increased happiness and life satisfaction. Lower positive schemas also interacted with negative components of PLEs to predict decreased life satisfaction and increased depressive symptoms over time. Implications for models of youth well-being and prevention/intervention efforts are discussed.