Journal of Social and Clinical Psychology 29(9): 949-974 This study examined whether deficits in dealing with daily problems emerge before a depressive episode (i.e., pre-existing vulnerability) or after a depressive episode (i.e., psychosocial scar). Participants completed a 30-day daily diary in which they reported their most negative event of the day, their appraisals of that event, and their mood. Three years later, they completed a structured depression interview. The sample consisted of 350 college students, 24 of whom had a past history of depression and 54 of whom experienced a depressive episode subsequent to diary completion. Multilevel modeling revealed that students with past depression blamed others more than the never-depressed and those with subsequent depression, which supported the scar hypothesis. In support of the vulnerability hypothesis, as compared to the never-depressed group, participants with past depression demonstrated steeper declines in positive mood on more stressful days but did not significantly differ from the subsequent-depression group. Overall, our findings do not provide clear support for either hypothesis; however, this study is the first to use a daily diary design to directly compare individuals with past depression to individuals who would subsequently experience depression.