Coronavirus disease (COVID-19)-related lockdown provided an opportunity to examine the relationship between affect and alcohol consumption in a historically unique context. To shed light on mixed findings regarding the interplay between affective states and alcohol consumption, the present study examined how affective states and affect fluctuations impact drinking during confinement of people to their homes. It also examined the extent to which the social context moderated the affect-consumption relationship. Having preregistered study protocols, methods, and hypotheses, 87 U.K. participants (34% male, M-age = 29.33) used their smartphones to respond to thrice daily prompts, recording their affective states, alcohol consumption, and social context over 1 week. Multilevel modeling suggested that being with someone (vs. alone) was associated with increased alcohol consumption. Increased drinking on the previous day was associated with increased next day negative affect, and the number of household occupants was associated with decreased negative affect. Preconsumption affect was not associated with subsequent drinking. These findings point to a complex relationship between alcohol consumption, social context, and negative affect. The opportunity to interact with others during lockdown was generally associated with decreased negative affect in the moment. However, the presence of others was associated with increased consumption which, in turn, predicted elevated next-day negative affect. Public Health Significance During lockdown, greater opportunity to interact with household members was associated with decreased negative mood in the moment, while being with someone was associated with increased alcohol consumption, which in turn was linked to increased next-day negative mood. This suggests that alcohol may attenuate the positive impact others may exert.