PROJECT ABSTRACT At a time when youth suicide and school shooting incidents are increasing, a growing number of U.S. schools are implementing commercially available social media surveillance (SMS) technology that can allegedly identify mental health and safety threats by monitoring students' social media posts. Although SMS technology is increasingly being purchased and used by schools, such use is often not disclosed to students or parents. There is also a lack of transparency regarding the methods used by companies to collect information about students, and there are no guidelines to inform how schools use and respond to the information they receive. Moreover, there is typically no evaluation of practice by schools, and there has been no systematic assessment of the ethical, legal, and social implications (ELSI), including how it affects the students whom it purportedly aims to help. We recently conducted a brief survey of 529 students, parents, teachers, and school administrators on perceptions of SMS. Compared to administrators, students were less supportive of using SMS, more skeptical of whether it could address violence, bullying, and mental health issues, and parents felt it could lead to data misuse and discrimination. These preliminary data point to differing perspectives among stakeholder groups and suggest more work is needed to assess the ways in which SMS is currently implemented and the range and complexity of possible effects on students. The long-term goal of this research is to promote the health, safety, and privacy interests of students and the institutional obligations and interests of schools by identifying and mitigating harms from school-based SMS. The overall objective of this application is to document the ways in which SMS is currently being used by school administrators, assess the perspectives of students and parents, and analyze the ELSI issues. Our hypothesis, based on our preliminary work, is that administrators engage in a wide range of implementation practices and that some youth are vulnerable to adverse effects of school-based SMS. The work proposed in this application is needed to inform student-centered policy recommendations in this area where little transparency and regulation currently exist. We propose the following specific aims: 1) Document school administrators' reasons for using SMS and current implementation practices; 2) Assess the perceived effects of school-based SMS on students and identify student characteristics associated with vulnerability to adverse effects; and 3) Conduct a detailed analysis of the ELSI issues with school-based SMS and develop policy recommendations. This project will generate new insights about perceptions and practices related to SMS in schools. Results could also inform a research agenda in this area, including whether systematic intervention studies of some school-based SMS systems are warranted, and if so, offer study design considerations that center the mental health...