To examine the preinjury rates of Axis I disorders and the prospective rates within the first 6 years after traumatic brain injury (TBI). Cross-sectional, longitudinal, and cross-sequential. Community-based research and training center. Persons (N=188) who had sustained TBI within 4 years of enrollment into the project were interviewed at either 2 and 3 assessments. Each assessment was approximately 1 year apart. Several Axis I diagnoses were analyzed to detect cross-sectional differences (by age and time postinjury) and average individual changes over the multiple measurement time points. Not applicable. Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders. The odds ratios changed longitudinally within each subject, indicating a decreased probability of having an Axis I diagnosis over time. There were few cross-sectional differences in age; therefore, age at the time of injury had little impact on Axis I diagnoses. Cross-sectional time since injury was not associated with more psychiatric disorders, whereas cross-sectional preinjury history of psychiatric disorders was predictive of postinjury psychiatric disorders. After controlling for cross-sectional effects, the frequencies of Axis I disorders increased in depression, anxiety, and posttraumatic stress disorders in the first assessment postinjury and declined in subsequent assessments. Cross-sequential analyses that control for cross-sectional and longitudinal differences produced a more complete description of psychiatric disorders after TBI.