Once certain approaches are put into practice, their effectiveness tends to diminish. The implementation process introduces variations in execution, and as a result, elements that were initially effective may no longer work as intended. In order to address the adherence to implemented approaches, the next crucial step is to focus on fidelity. Fidelity refers to the extent to which a program implementing evidence-based practices aligns with the standards and principles outlined in a program model. Measuring fidelity enables researchers and practitioners to enhance their comprehension of the mechanisms and reasons behind intervention effectiveness. A growing number of researchers emphasize the importance of proper fidelity assessment, but in practice it is still used very little. As part of the scale-up process of the STORM approach scale-up process, a fidelity scale will be developed for the purpose of evaluating and ensuring implementation fidelity and quality. The first step in developing a suitable scale for the STORM approach will be presented. We extensively studied existing literature to gain an overview of the current use of fidelity scales. We conducted a systematic review on fidelity assessments within depression-, anxiety- and suicide prevention programs, using literature databases Embase, ERIC, MEDLINE, and PsycINFO. The preliminary results yielded 100 eligible articles showing that the majority of the studies did not sufficiently report on fidelity measurements. The systematic review will provide evidence for the components of a fidelity measurement scale to enhance that adolescents will receive the most effective STORM approach. The further process of constructing a fidelity scale, as outlined by Bond and Drake (2020), involves three key steps: (1) defining scale content, (2) formulating data collection procedures, and (3) evaluating psychometric properties. These steps will also be taken in this research. Eventually, the application of a fidelity measurement tool can significantly enhance the probability that the target population receives the most scientifically rigorous treatment. The symposium will feature a presentation on the project and the initial findings from the systematic review.