Behavioral interventions to reduce hazardous drinking are only moderately successful in promoting sustained behavior change and post-intervention effect sizes among adolescents remain modest. This study aimed to explore a relevant therapeutic active ingredient, adolescent:provider alliance, as a moderator of short-term (3 month) adolescent intervention outcomes within the course of a larger parent randomized control trial (RCT).

Participants were community-based youth engaged in hazardous drinking (N = 168) who were randomized to 2 sessions of either motivational interviewing (MI) or mindfulness (brief adolescent mindfulness; BAM). Youth reported pre-intervention hazardous drinking at baseline and rated therapeutic alliance (a metric of adolescent:provider “connectedness” that helps facilitate working relationships during interventions) immediately post-intervention; they reported hazardous drinking again at 3 months post-intervention. Negative binomial regressions predicted post-intervention hazardous drinking score from adolescent:provider alliance, intervention condition, and their interaction.

Mean hazardous drinking was reduced by 34–40 % across both intervention conditions, with no significant between-condition differences. Stronger adolescent:provider alliance was associated with lower hazardous drinking scores at 3 months, but this effect was attenuated after controlling for baseline hazardous drinking. Contrary to predictions, adolescent:provider alliance did not appear to moderate the effect of intervention condition in this sample of young people engaged in hazardous drinking.

Consistent with prior literature, baseline hazardous drinking was a robust predictor of treatment outcomes. At the same time, these results suggest that future work may benefit from continuing to examine and disaggregate the nature of adolescent:provider alliance across the spectrum of empirically supported brief interventions for adolescent hazardous drinking.

Clinical Trials Registration Number: ClinicalTrials.gov identifier: NCT03367858.

Data Sharing Statement: Requests for deidentified individual participant data can be made to the first author.