Background: Currently, approximately 100 million people are displaced worldwide, including children and young adults. Previous studies showed exposure to violence and posttraumatic stress disorder (PTSD) are common in this sub-population. However, we still lack comprehensive data on well-being, mental health, and the ability to function. Methods: This study included 291 adolescent (aged 12-17 years) and young adult (18-25 years) refugees recruited nationwide in Sweden between 2019 and 2022. Sociodemographic, mental health and well-beingrelated data (well-being, post-traumatic stress symptoms, psychiatric diagnoses, and functional ability) were collected using semi-structured interviews with structured components. Associations between accompanied status and well-being/depression/suicidal thoughts, generalized anxiety disorder/panic disorder/PTSD symptoms, and functional ability were analyzed using linear and logistic regression, adjusted for age, gender, parental education, asylum status, and region of origin. Findings: Most study participants (mean age 17.9 years) originated from the Middle East and North Africa (70.6 %) or Sub-Saharan Africa (27.0 %). 16.1 % of adolescents and 32.3 % of young adults were unaccompanied. Nearly the entire study sample had experienced violence (92.8 %). However, the sample had a low prevalence of psychiatric diagnoses. For example, only 5.9 % fulfilled the criteria for clinical depression. Self-reported wellbeing (WHO-5, 71.09 (23.91)) and observer-rated functional ability (GAS/GAF, 81.76 (14.15)) were high. There were no significant differences in diagnosis prevalence by gender. However, significant differences existed between accompanied versus unaccompanied groups. Being an unaccompanied refugee individual was associated with a higher risk of suicidal thoughts, adjusted odds ratio, aOR 5.66 (95 % CI 2.15-14.88), higher rates of posttraumatic stress disorder symptoms /3 = 0.72 (0.39-1.05), lower mental well-being /3 = -10.86 95 % CI (- 18.23- -3.48) and lower functional ability /3 = -9.38 (- 13.84- -4.92). There were no differences in outcomes by gender except for worse well-being in males (/3 = 6.83 (1.01-12.66)). Interpretation: In this sample, we found lower prevalence rates for all psychiatric diagnoses compared to earlier published studies. Being an unaccompanied refugee individual was a risk factor for all adverse outcomes. Future studies need to confirm the relatively low rates of psychiatric diagnoses. Regardless, the results highlight the heterogeneous needs among newly arrived refugees.