Objective: Most studies on posttraumatic growth (PTG) have focused on personal characteristics, interpersonal resources, and the immediate environment. There has been less attention on dynamic internal processes related to the development of PTG and on how these processes are affected by the broader culture. Calhoun and Tedeschi’s (2006) model suggests a role of distal culture in PTG development, but empirical investigations on that point are limited. The present study investigated the role of social complexity—the generalized belief about changing social environments and inconsistency of human behavior—as a predictor of PTG. Social complexity was hypothesized to be associated with problem-solving approaches that are likely to give rise to cognitive processes that promote PTG. Method: A sample of 446 survivors of Typhoon Haiyan, 1 of the strongest typhoons ever recorded at the time, answered self-report measures of social complexity, cognitive processing of trauma, and PTG. Results: Structural equation modeling indicated a good fit between the data and the hypothesized model; belief in social complexity predicted stronger PTG, mediated by cognitive processing. Conclusion: The results provide evidence for how disaster survivors’ beliefs about the changing nature of social environments and their corresponding behavior changes are predictors of PTG and suggest a psychological mechanism for how distal culture can influence PTG. Thus, assessing social complexity beliefs during early the phases of a postdisaster psychosocial intervention may provide useful information on who is likely to experience PTG. Trauma workers might consider culture-specific social themes related to social complexity in disaster-affected communities.