Understanding the purpose behind creating a personality assessment file directly affects its practical implementation. The clearer and more justified its rationale, the more useful it becomes in judicial decision-making. The reasoning for establishing such files for juvenile offenders shares both similarities and differences with adult cases. While shared features might reduce the need for a distinct approach, the differences strengthen its necessity in the juvenile context. Similarities include legal ambiguities: unclear legal status of the file, its separation from the main criminal case, limiting its use to serious offences, and a lack of defined mechanisms for how it affects court proceedings. In contrast, juvenile files emphasize age-based assessments, broader applicability to most juvenile offences, and provisions tailored to youth development. Despite these justifications, the compilation process for juveniles often mirrors that of adults. This study, using descriptive and analytical methods with library sources and field observations from the Tehran Juvenile Prosecutor’s Office, examines both the rationale and practical implementation of these files. Findings show that a lack of clear purpose, incomplete legislation, and absence of judicial policy have limited the file’s effectiveness in juvenile cases. The study recommends legal reform and the adoption of content-driven, not form-based, strategies to improve outcomes. It also suggests that relevant information, such as causes and background of the offence, could be integrated into the main criminal file, making a separate structure unnecessary while still serving the file’s intended function.