Background: Posttraumatic stress disorder (PTSD) and depression are the most prevalent mental disorders following disasters, and they often co-occur. The current study investigated trajectories of PTSD and depression among children after exposure to the Wenchuan earthquake and identified factors associated with PTSD or depression trajectories. Methods: Three hundred children who were exposed to the Wenchuan earthquake reported PTSD and depression symptoms 4, 16, 29, 40 and 52 months after the disaster, and potential predictors (age, earthquake exposure, prequake trauma and parental relationship) were identified. The PTSD and depression trajectories were identified with latent growth mixture modeling (LGMM), and the predictors were explored with multinomial logistic regression. Results: Two depression trajectories emerged: resilient (66.2%) and chronic (33.8%). Three PTSD trajectories emerged: resilient (74.9%), recovery (7.5%) and relapsing (17.7%). Overall, 57.3% of the children had low depression and PTSD symptoms over four years. Depression trajectories were significantly predicted by age and parental relationship, while PTSD trajectories were significantly predicted by trauma exposure and prequake trauma experience. Limitations: The children's prequake mental health statuses were unknown, and all assessments relied on self report questionnaires. Conclusion: The postdisaster developmental course of depression was more stable than that of PTSD, and PTSD and depression had different risk factors. Previous studies that focus only on PTSD or depression trajectories may overestimate children's resilient responses. Longer-term postdisaster intervention should pay more attention to depression than to PTSD.