Objectives: The objectives of this study were as follows: to present a concise overview of the sample, outcomes, determinants, non-response and attrition of the ongoing TRacking Adolescents' Individual Lives Survey (TRAILS), which started in 2001; to summarize a selection of recent findings on continuity, discontinuity, risk, and protective factors of mental health problems; and to document the development of psychopathology during adolescence, focusing on whether the increase of problem behavior often seen in adolescence is a general phenomenon or more prevalent in vulnerable teens, thereby giving rise to diverging developmental pathways. Method: The first and second objectives were achieved using descriptive statistics and selective review of previous TRAILS publications; and the third objective by analyzing longitudinal data on internalizing and externalizing problems using Linear Mixed Models (LMM). Results: The LMM analyses supported the notion of diverging pathways for rule-breaking behaviors but not for anxiety, depression, or aggression. Overall, rule-breaking (in both genders) and withdrawn/depressed behavior (in girls) increased, whereas aggression and anxious/depressed behavior decreased during adolescence. Conclusions: TRAILS has produced a wealth of data and has contributed substantially to our understanding of mental health problems and social development during adolescence. Future waves will expand this database into adulthood. The typical development of problem behaviors in adolescence differs considerably across both problem dimensions and gender. Developmental pathways during adolescence suggest accumulation of risk (i.e., diverging pathways) for rule-breaking behavior. However, those of anxiety, depression and aggression slightly converge, suggesting the influence of counter-forces and changes in risk unrelated to initial problem levels and underlying vulnerability. (Contains 2 figures and 6 tables.)