["Addiction, Volume 121, Issue 7, Page 1850-1862, July 2026. ", "\nAbstract\n\nBackground and aims\nHarmful alcohol consumption remains widespread among university students and is associated with numerous academic, social and health‐related consequences. Peer‐led approaches offer a promising strategy to reduce risky drinking in this population. This study evaluated the long‐term effects of a peer‐led Brief Alcohol Screening and Intervention for College Students (BASICS) program.\n\n\nDesign\nA parallel two‐group randomised controlled trial with a follow‐up period of 12 months was conducted.\n\n\nSetting\nThe study took place at a university in Spain.\n\n\nParticipants\nA total of 308 undergraduate students who had engaged in at least one episode of heavy drinking in the previous month were randomly assigned to either the intervention group (n = 154) or the control group (n = 154).\n\n\nIntervention\nThe intervention group received a single individual session of the peer‐delivered BASICS program. The control group received no intervention during the study period.\n\n\nMeasurements\nThe primary outcome was the number of alcoholic drinks consumed during a typical week at the 12‐month follow‐up. Secondary outcomes included weekly drinking at one month, as well as weekend drinking, drinks on the heaviest occasion, binge drinking episodes, peak blood alcohol concentration during a typical week and on the heaviest occasion, alcohol‐related consequences, motivation to reduce alcohol use and self‐efficacy, all of which were assessed at both 1 and 12 months.\n\n\nFindings\nAt the primary 12‐month follow‐up, statistically significant between‐group differences were observed for all nine measured outcomes. For the primary outcome, the mean weekly alcohol consumption was 8.93 drinks [95% confidence interval (CI) = 7.7–10.2] in the intervention group and 12.35 drinks (95% CI = 11.1–13.6) in the control group. The between‐group difference was 3.42 drinks (95% CI = 1.66–5.18), indicating lower consumption in the intervention group. Among the secondary outcomes, statistically significant differences were also observed for weekend drinking (3.08 drinks, 95% CI = 1.59–4.56), drinks on the heaviest occasion (3.27 drinks, 95% CI = 1.79–4.76), binge drinking frequency (0.93 episodes, 95% CI = 0.54–1.32) and alcohol‐related consequences (3.28 points, 95% CI = 1.74–4.82).\n\n\nConclusions\nAmong Spanish college students who had engaged in at least one episode of heavy drinking in the previous month, a single peer‐led Brief Alcohol Screening and Intervention for College Students (BASICS) session produced sustained improvements in alcohol use, related consequences, and psychological mediators up to 12 months post‐intervention.\n\n"]