OBJECTIVE: The development of a new weight-related measure to assess quality of life in adolescents [Impact of Weight on Quality of Life (IWQOL)-Kids] is described. RESEARCH METHODS AND PROCEDURES: Using a literature search, clinical experience, and consultation with pediatric clinicians, 73 items were developed, pilot tested, and administered to 642 participants, 11 to 19 years old, recruited from weight loss programs/studies and community samples (mean z-BMI, 1.5; range, -1.2 to 3.4; mean age, 14.0; 60% female; 56% white). Participants completed the 73 items and the Pediatric Quality of Life Inventory and were weighed and measured. RESULTS: Four factors (27 items) were identified (physical comfort, body esteem, social life, and family relations), accounting for 71% of the variance. The IWQOL-Kids demonstrated excellent psychometric properties. Internal consistency coefficients ranged from 0.88 to 0.95 for scales and equaled 0.96 for total score. Convergent validity was demonstrated with strong correlations between IWQOL-Kids total score and the Pediatric Quality of Life Inventory (r = 0.76, p < 0.0001). Significant differences were found across BMI groups and between clinical and community samples, supporting the sensitivity of this measure. Participants in a weight loss camp demonstrated improved IWQOL-Kids scores, suggesting responsiveness of the IWQOL-Kids to weight loss/social support intervention. DISCUSSION: The present study provides preliminary evidence regarding the psychometric properties of the IWQOL-Kids, a weight-related quality of life measure for adolescents. Given the rise of obesity in youth, the development of a reliable and valid weight-related measure of quality of life is timely.