The authors examined whether the associations among daily positive and negative interpersonal events, alcohol consumption, and affect varied as a function of naltrexone or placebo administered in a targeted (in anticipation of or in response to high-risk drinking situations) or daily fashion. Heavy drinkers (N = 149) received 4 sessions of brief coping skills counseling in addition to 8 weeks of naltrexone treatment. They recorded for 8 weeks in structured nightly diaries their interpersonal interactions, affect, and alcohol consumption. The authors predicted that participants receiving naltrexone, compared with those taking placebo, would drink less in response to interpersonal encounters and that naltrexone administration would attenuate the link between positive interpersonal events and positive affective states. Results indicated that both positive and negative interpersonal interactions were associated with an increased probability of engaging in any drinking and that positive daily social celebratory events were associated with an increased probability of engaging in heavy drinking. Participants taking naltrexone in a targeted fashion showed the strongest positive association between the number of positive social celebratory events and drinking. Although this finding was inconsistent with the overall reduction in drinking that has been generally reported for those treated with naltrexone, positive social celebratory events occurred on only a minority of days. Participants taking naltrexone, compared with those taking placebo, showed weaker associations between positive social celebratory events and positive and negative affective states. Findings are discussed in terms of naltrexone's dampening effects on the rewarding properties of alcohol use and certain positively valenced stimuli.