Family history of alcoholism (FHA) is posited to convey its risk on problematic drinking, in part, though how individuals react to stressful situations. Research thus far, however, has found equivocal results, with some studies concluding that FHA is associated with heightened stress-reactivity whereas others have found FHA associated with blunted stress-reactivity. In addition, the preponderance of this research has been conducted using laboratory-based paradigms, thus raising questions about the ecological validity of their findings. The purpose of the current study was to further clarify the association between FHA and affective reactions to two types of stress (social and academic stress) using an ecologically valid, micro-longitudinal research design. Participants were 1,606 undergraduate students (54% women) who completed a baseline survey, including questions related to both maternal and paternal alcohol use, and who subsequently completed a 30-day daily diary in which they reporting on their daily social and academic stress and affective states. Results showed a weaker positive association between social stress and anxiety among individuals with more paternal FHA symptoms, consistent with a blunted stress-reactivity perspective. The current study is the first to use an ecologically valid approach to investigate stress-reactivity in individuals with and without FHA. The results add to the current literature, providing a direction for future research to continue to clarify the nature FHA and stress-reactivity in order to understand the risk incurred by FHA.