Self-determination theory (SDT) proposes that people are more likely to engage in behaviors that reduce the harms associated with alcohol use if they do so for more self-determined reasons. There is growing support for this proposal, but the Treatment Self-Regulation Questionnaire (TSRQ), which assesses the self-determination continuum of motivation for engaging in alcohol-related harm reduction behaviors, lacks content coverage. We generated additional items to improve the content coverage of the TSRQ and evaluated its psychometric properties. We also compared two randomly assigned instruction sets that referenced "responsible drinking" or "protective behavioral strategies" (PBS). Participants (n = 2,236) were college students from psychology departments at 10 universities in eight U.S. states who reported past-month alcohol use and completed the revised TSRQ; the online survey was completed for partial course credit. Exploratory factor analysis supported a three-factor structure representing autonomous motivation, controlled motivation, and amotivation for the PBS version. This factor structure was confirmed using exploratory structural equation modeling for both the PBS and responsible drinking versions. Scalar invariance was achieved across instruction sets. Latent mean differences showed that those who received the PBS version had lower autonomous and controlled motivation scores, but higher amotivation scores. Associations of the three TSRQ factors with alcohol-related outcomes were consistent with SDT, and the magnitude of these associations did not differ across instruction sets. More accurate assessment of the self-determination continuum of motivation for alcohol-related harm reduction behaviors will improve research on this topic which has promising implications for alcohol interventions. (PsycInfo Database Record (c) 2024 APA, all rights reserved).