The Trajectory of Adolescent Mental Health: The Effects of Parental Divorce and Marital Conflict during Childhood ABSTRACT Using a nationally representative dataset (Taiwan Education Panel Survey, TEPS), this study examined the effect of parental divorce and marital conflict during childhood on adolescent mental health, including happiness and depressed mood. The final sample comprised 3,886 adolescents. Results from Hierarchical Linear Regression (HLM) demonstrated that both parental divorce and marital conflict during childhood reduced the initial level (grade 7th) of adolescent happiness, and increased the initial level (grade 7th) of adolescent depressed mood. Furthermore, adolescents from families with parental divorce (occurring when they were 0~12 years old) with pre-divorce marital conflict have the lowest happiness and highest depressed mood, even worse than adolescents from two-parent families with marital conflict. Keywords: Adolescent mental health, parental divorce, parental marital conflict, HLM