Although the majority of trauma patients are discharged home rather than to a rehabilitation facility, the timeliness of their return to function (RTF) has received little study. The present prospective study attempted to identify those factors that would predict delayed RTF. The study group consisted of patients admitted to a level I trauma center for at least 24 hours, who were of working age (18-64 years), who passed a cognitive screening examination, and who were discharged home. Demographic data and psychological profiles were collected on all participants. Patients were followed by telephone at approximately 1 1/2, 3, and 6 months after discharge. Five hundred seventy patients were entered into the study; complete follow-up data were available for 441. Statistical methods were modeled after survival analysis using a proportional hazards multiple regression to identify variables prognostic of RTF time. This type analysis is independent of time, providing a "risk" of RTF at any point in time after the injury. It also allowed the calculation a relative hazards ratio (RHR), which quantifies the impact of a prognostic variable on RTF time. Injury Severity Score (ISS) and age were found to be associated with RTF (p < 0.0001 for each). After correcting for ISS and age, five additional factors were found to be associated with RTF. Higher educational level and living in a non-family household were associated with faster RTF. Less than 100% income replacement by disability income, pre-injury hostility, and litigation related to the injury were associated with slower RTF. There were a number of other demographic, work-related, and psychosocial factors that were not related with RTF.(ABSTRACT TRUNCATED AT 250 WORDS)