Although exposure to stress is a central component of the stress process paradigm, little research has explicitly sought to identify antecedents of stress exposure. Based on a probability sample of 1393 adults aged 18-55 residing in Toronto, Canada, this research examines the effects of social status, past adversity, social and personal resources and history of mental disorder on recent exposure to stress. Consistent with earlier findings, results indicate that younger adults, divorced individuals and those with lower socioeconomic status, experience greater levels of social stress. Although respondent's history of major depressive disorder was related to all types of stress exposure, past cumulative adversity was the most powerful predictor of both total current stress (operant burden) and the subsequent onset of life events, independent of other antecedents. Findings suggest that the onset of chronic stress is more affected by personal characteristics, such as emotional reliance and disorder history, than is onset of life events. Implications of these findings are discussed.