U.S. public school students increasingly attend schools with sworn law enforcement officers present. Yet little is known about how these school resource officers (SROs) affect school environments or student outcomes. Our study uses a fuzzy regression discontinuity (RD) design with national school-level data from 2014 to 2018 to estimate the impacts of SRO placement. We construct this discontinuity based on the application scores for federal school-based policing grants of linked police agencies. We find that SROs effectively reduce some forms of violence in schools, but do not prevent gun-related incidents. We also find that SROs intensify the use of suspension, expulsion, police referral, and arrest of students. These increases in disciplinary and police actions are consistently largest for Black students, male students, and students with disabilities.

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学校中的细蓝线：美国各地学校治安的新证据

美国公立学校的学生越来越多地在有宣誓执法人员在场的学校就读。然而，人们对这些学校资源官员 (SRO) 如何影响学校环境或学生成绩却知之甚少。我们的研究使用模糊回归不连续性 (RD) 设计和 2014 年至 2018 年全国学校层面的数据来估计 SRO 安置的影响。我们根据相关警察机构的联邦学校治安补助金申请分数构建了这种不连续性。我们发现，SRO 有效减少了学校中某些形式的暴力，但并不能防止与枪支有关的事件。我们还发现，SRO 强化了对学生的停学、开除、警察移交和逮捕。这些纪律和警察行动的增加对于黑人学生、男学生、