DynaM-OBS is a nine-month, multi-centre longitudinal study across five European sites and Tel Aviv, investigating resilience in healthy young adults with past adversity and elevated mental health problems. It aims to identify mechanisms that help individuals maintain good mental health despite adversity, informing future interventions. The study recruited participants from Berlin, Germany; Mainz, Germany; Nijmegen, The Netherlands; Tel Aviv, Israel; and Warsaw, Poland. A total of 259 participants were assessed at baseline, and 223 completed the entire study period. The participants were assessed longitudinally over a period of 9 months. The study includes: (1) a comprehensive baseline assessment of social, psychological, and biological resilience factors; (2) biweekly online monitoring of stressors and mental health for 6 months, then monthly for 3 months; (3) repeated assessment of resilience factors over time; and (4) monthly week-long ecological momentary and physiological assessments of mood and stress via smartphones and wearables. Included participants reported at least three past stressful life events, as well as an elevated level of internalising mental health problems, but were not presently affected by any mental disorder other than mild depression.