Exposure to stress and traumatic experiences in children and adolescents may hinder development and contribute to the development of mental disorders. Over the recent decade, significant updates have been made to the conceptualisation of human responses to adverse life experiences. The majority of studies in traumatic stress have been conducted in the adult population. However, there is a lack of understanding of how the proposed new conceptualizations reflect the complexity of traumatic stress in youth. Furthermore, there are debates on the role of resilience in coping with stress and trauma. The symposium is grounded on the findings of the large-scale longitudinal study on Vilnius Stress and Resilience in Adolescence (STAR-A). The presentations in this symposium will outline the new developments in methodology and challenges in the research of abuse and trauma in adolescence. Further, an innovative research on complex posttraumatic stress in adolescence, including a longitudinal and cross-cultural perspective, will be presented. Empirical evidence on the longitudinal effects reveals a complex interaction and trajectories between mental health and resilience. Finally, novel directions for psychosocial support for adolescents with high stress levels will be presented, focusing on innovative digital interventions.