This study addresses the longstanding clinical impression that episodes of endogenous depression have less relationship to environmental stress than episodes of nonendogenous depression. Stress levels of 100 Research Diagnostic Criteria-assessed psychiatric inpatients are retrospectively assessed for the period immediately before episode onset and for an earlier, baseline period. Although pre-episode stress levels are higher in nonendogenous depressed patients than in endogenous depressed patients or psychiatric controls, this difference is due to a higher baseline level in the nonendogenous group. Compared longitudinally, all three groups show an equivalent increase in stressful events from the baseline to pre-episode period.