The primary purpose of this book was to add to the current state of knowledge on the role of cognitive factors in the understanding of depressed mood and changing incidence rates in adolescents. The longitudinal study described in this book was designed to address the following questions:(a)Are there correlations between depressed mood and attributional style,beliefs regarding the stability of traits, and levels of rumination? (b) Are older children more likely to experience depressive moods than younger children? (c) Are there any gender differences in depressed mood, attributional style, beliefs regarding stability of traits, and rumination level? (d) Which of these factors, or combination of factors, demonstrates the ability to predict depressed mood over time? The study’s results support previous research that has shown correlations between depression and attributional style, depression and beliefs about stability of traits, and depression and rumination.