During the transition from high school to college, youths navigate increasingly adult roles, take on new academic and economic responsibilities, and forge new social networks. We examined longitudinal relations among internalizing symptoms (depression and anxiety), perceived social support, and the personality trait of ego-resiliency across three time points at the end of high school and during the first year of college (N = 82). Internalizing symptoms were concurrently negatively correlated with perceived social support from friends and family as well as with ego-resiliency, and ego-resiliency was positively, concurrently correlated with perceived social support from friends. Across time, internalizing symptoms were negatively associated with perceived social support from friends, whereas ego-resiliency was positively associated with perceived social support from family. Findings demonstrate the potential importance of coping resources for youths’ mental health and highlight the negative associations between internalizing symptoms and later perceptions of social support during this transitional stage.