Abstract Background Training is a core component in the implementation of empirically supported treatments, especially in the case of psychosocial interventions targeting mental illness. However, common forms of training are relatively ineffective in producing behavioral changes in providers. Trainers are in a strategic position to influence the success of training, but no research, to our knowledge, has explored whether personal characteristics of trainers (e.g., enthusiasm, charisma) increase effectiveness of training empirically supported treatments in the field of mental health. To address this gap, the current study created a measure of trainer characteristics (the Measure of Effective Attributes of Trainers (MEAT)) and assessed preliminary evidence for its reliability and validity by following gold standard measure development procedures. Methods Measure development consisted of three steps: (1) An initial pool of items was generated based on extant literature, input from the target population, and expert input; (2) target users of the measure interacted with the initial item pool to ensure face validity as well as clarity of measure instructions, response options, and items; and (3) a convenience sample viewed training videos and completed the measure resulting from step 2 to establish preliminary evidence of reliability and validity. An exploratory factor analysis was performed on the measure to determine whether latent factors (i.e., subscales of characteristics) underlie the data. Results The final solution consisted of two factors that demonstrated preliminary evidence for structural validity of the measure. The first factor, labeled “Charisma,” contained items related to characteristics that facilitate a positive personal relationship with the trainee (e.g., friendly, warm), and the second factor, labeled “Credibility,” contained items related to characteristics that emphasize the qualification of the trainer (e.g., professional, experienced). There was also evidence for face validity, content validity, reliability, and known groups validity of the measure. Conclusions The MEAT demonstrated preliminary evidence of key psychometric properties. Future research is needed to further explore and contribute to its psychometric evidence, which could be done in conjunction with measures of trainee knowledge, attitudes towards empirically supported treatments, and evaluations of trainee behavior change to delineate key characteristics of trainers to be leveraged for more effective training.