Thesis advisor: Jacqueline V. Lerner / This dissertation considered character development in adolescence from a relational developmental systems (RDS) perspective through the estimation of trajectories of five character attributes and the associations of these trajectories with the contextual factors of intentional self-regulation (ISR) and prosocial socialization from role models whom adolescents reported knowing personally. Character attributes considered were honesty, humility, diligence, future mindedness, and purpose. Data were taken from the Connecting Adolescents' Beliefs and Behaviors longitudinal study of character development in adolescents from the Northeastern United States. Results demonstrated that multiple trajectories can be estimated for each character attribute, supporting the RDS principles of plasticity and individual differences. Associations were also found among all character attributes considered at every time point. Contextual factors had more nuanced relationships with character attribute trajectories than was expected, with high levels of ISR associated with high start points for all character attributes and for overall character attribute patterns, but not necessarily with sustained high levels of character attributes. Prosocial socialization did not demonstrate a stable association with high levels or increasing levels of any character attribute examined. This pattern of findings suggests that additional contextual aspects should be considered as important aspects of character development. Limitations and future directions are discussed. / Thesis (PhD) — Boston College, 2019. / Submitted to: Boston College. Lynch School of Education. / Discipline: Counseling, Developmental and Educational Psychology.