<p>Family, peers, and teachers are the three pillars that significantly shape adolescents’ lives. Traumatic events originating from these domains (i.e., family, peers, and teachers) can have profound implications on adolescents’ mental health. Using a three-wave dataset with a 6-month interval, this study investigated 2,166 Chinese adolescents (51.9% girls, <i>M</i>_age = 13.44 ± 0.72), who completed questionnaires assessing family adversity, peer victimization, and teacher maltreatment at Time 1, cognitive emotion regulation strategies at Time 2, followed by assessments of complex posttraumatic stress disorder (CPTSD) symptoms at Time 3. The latent profile analysis and Bolck, Croons, and Hagenaars (BCH) method were used for data analyses. Four groups were identified: low risk (82.6%, <i>n</i> = 1,790), family adversity (6.5%, <i>n</i> = 140), peer adversity (7.8%, <i>n</i> = 170), and multiple adversities (3.0%, <i>n</i> = 66). The direct model showed that compared with the “low risk” group, adolescents in the “family adversity” and “peer adversity” groups showed a significantly higher risk of developing CPTSD symptoms. Additionally, compared with the “low risk” group, adolescents in the “family adversity,” “peer adversity,” and “multiple adversities” groups exhibited higher level of CPTSD symptoms only through increased rumination. These findings underscore the critical impact of adversity from family, peers, and teachers on the mental health of adolescents, highlighting the importance of targeted interventions on rumination to mitigate the risk of CPTSD in these vulnerable groups.</p>