When are bystanders more likely and confident to act: Validation of the Bystanders to Alcohol Risk Scales—Willingness and self-efficacy.

OBJECTIVE: This study evaluated the psychometrics of two new measures of willingness and self-efficacy to intervene in alcohol-related risk situations involving others. Items assess the constructs across bystander scenarios that vary by situation (before, during, after risk), one's relation to the target (friend/stranger), and the gender of the target (man/woman). METHOD: 22.0 years, 46.0% women, 70.7% White, 23.3% Latinx) completed the new measures and related measures to assess validity, and a subsample was retested 2 weeks later. Multivariate variance decomposition was used to determine how the scenario components influenced variance; bivariate correlations evaluated validity, and intraclass correlations evaluated test-retest reliability. RESULTS: Models for willingness and self-efficacy constructs fit the data well. The largest component contributing to both measures was the general component, reflecting overall willingness/self-efficacy regardless of situation, relation, and gender components (αs > .90). For willingness, the next largest component was situation, with "after" drinking showing the greatest variability but the lowest mean. For self-efficacy, the second most important component was relation to the target, with friend showing higher self-efficacy than stranger. Participants indicated higher willingness and self-efficacy when the target was a woman, and women participants reported higher willingness than men. Validity was supported by significant correlations with bystander behaviors and alcohol-related constructs. Test-retest reliability indicated moderate stability for both measures (intraclass correlations = 0.50-0.64). CONCLUSIONS: These measures provide valid and reliable tools for measuring bystander intervention willingness and self-efficacy in alcohol-related risk situations and offer utility for the evaluation of bystander intervention programs. (PsycInfo Database Record (c) 2026 APA, all rights reserved).