Social drinking is one of the most common reasons for drinking among young people. Excessive alcohol consumption alters affective and reward brain function, and entails risks for mental health problems. To understand of the effect of early social drinking on real-life and neural reward functions is of particular importance. 378 community-based young healthy social drinkers (13 to 28 years) took part in a 7-day Ecological momentary assessment protocol using GPS-triggered smartphone-based e-dairies with 9 to 23 prompts per day to rate momentary affective well-being. Only self-identified current drinkers (mild-to-moderate) were included in analyses (endorsed drinking ≥1 time in month). Participants also completed a standard battery of questionnaires. Of those, 214 participants additionally completed a functional MRI with a well-established reward paradigm. We performed an activation and Psychophysiological interaction (PPI) analysis with ventral striatum (VS) as a seed-region.Higher weekly alcohol consumption was related to larger social network size (p = 0.015), risky social environment (p <0.00), and perceived loneliness (p=0.016), highlighting the inherent social component. Our data further show the alcohol-use related alterations in real-life affective well-being, indexed by valence, calmness, and energetic arousal (all ps<0.043). We further identified aberrant VS activity (pFWE=.044), and frontostriatal connectivity in the reward-processing circuitry (pFWE=0.006) linked to drinking behavior. These results suggest for possible disruptions in the striatal-prefrontal integration related to alcohol use rather than global reward anticipation.