Researchers have studied the efficacy of motivational interviewing over the past 30 years. While it is recognized as a highly effective approach overall, variability in outcomes studies is largely attributed to the extent to which it is implemented with fidelity. MI applications in school have become increasingly popular in the past 10 years, yet no reviews have included a comprehensive description of the prevalence and type of school-based MI applications or positioned MI training and fidelity monitoring in the broader framework of implementation science. The present scoping review documents the prevalence and type of MI applications, training strategies and techniques, and fidelity monitoring systems reported in school-based MI research. We identified 62 studies from 8 countries via a multi-step search and review process conducted iteratively between February 2020 and April 2023. For inclusion, articles needed to (a) be peer-reviewed, (b) school-based, (c) describe the use of MI as a primary intervention strategy, and (d) employ a rigorous research design. The results indicated most articles were published since 2012 and the most frequent target behavior was social-emotional, behavioral, or related difficulties. Less than one-third of the articles in the review contained information on the trainer's qualifications. Although MI was an active ingredient in all the studies and 71% indicated that they collected or monitored at least one dimension of intervention fidelity, less than half collected or monitored MI quality as a fidelity indicator. We conclude the lack of transparency in training and limited MI fidelity data among these studies make the evidence base for MI use within educational settings difficult to interpret. We discuss implications for the field and recommendations for future research.