Self-efficacy is a commonly examined cognitive determinant of behavior change in weight-loss trials, but there has been little uniformity in its measurement. To address this, a recently developed survey captures self-efficacy as it relates to three behavioral domains of interest to weight-loss interventionists: physical activity (PA), healthful eating, and weight loss. The purpose of this study was to test the psychometric properties of the Brief Weight-Loss-Related Behavior Self-Efficacy Scales in a large sample (n = 599) of adults with prediabetes. Participants completed the self-efficacy survey, as well as measures of PA, dietary intake, weight, and height. The factor structure was scrutinized using exploratory and confirmatory factor analysis, which supported a factor structure with three correlated first-order latent self-efficacy factors, specific to PA, healthful eating, and weight loss. This model is statistically equivalent to a hierarchical model including a second-order factor for overall behavioral weight-management self-efficacy. Measurement equivalence/invariance between relevant demographic groups was also supported by tests for equivalence of covariance matrices. Bivariate correlations between self-efficacy factors and measures of PA, dietary intake, and weight support the concurrent validity of score interpretations. Overall, these psychometric analyses support the validity of these scales' scores as independently reflective of self-efficacy for PA, healthful eating, and weight loss. This instrument is useful in clinical research to identify the cognitive drivers of weight loss and weight loss-inducing behavior. (PsycInfo Database Record (c) 2021 APA, all rights reserved).