Schools have become a primary context for assessing and addressing social, emotional, and behavioral difficulties in response to the youth mental health crisis. However, traditional paper-based assessments are often hindered by time constraints and rater bias, limiting their effectiveness for early identification and intervention. Technology-mediated assessments, such as smartphone-based ecological momentary assessment (EMA), offer potential solutions to these limitations. Despite their increasing use in clinical and research settings, their validity for school-based assessment remains largely unexplored. This interdisciplinary scoping review synthesized literature from fields such as clinical psychology, psychiatry, and education to examine technology-mediated youth mental health assessments relevant to schools. A systematic search identified ten studies that provided validity evidence for at least one of five methodologies: smartphone-based EMA, passive smartphone measures, wearable sensors, motion-tracking technology, and virtual reality assessment. While these technologies show promise in clinical and research settings, no studies systematically evaluated their validity for school-based screening, progress monitoring, or diagnostic decision-making in preK-12 settings. Most notably, there was no research on the social consequences of these assessments. These findings highlight a critical gap in research on the appropriateness of these assessments for schools. Without validation in school populations, their use risks unintended consequences, including misinterpretation of results and inequitable implementation. Future research must rigorously examine the validity, and especially the consequential validity, of these assessments in school settings to ensure they enhance rather than compromise mental health support for students.