The School-to-Prison Pipeline is a social phenomenon where students become formally involved with the criminal justice system as a result of school policies that use law enforcement, rather than discipline, to address behavioral problems. A potentially important part of the School-to-Prison Pipeline is the use of sworn School Resource Officers (SROs), but there is little research on the causal effect of hiring these officers on school crime or arrests. Using credibly exogenous variation in the use of SROs generated by federal hiring grants specifically to place law enforcement in schools, I find evidence that law enforcement agencies learn about more crimes in schools upon receipt of a grant, and are more likely to make arrests for those crimes. This primarily affects children under the age of 15. However, I also find evidence that SROs increase school safety, and help law enforcement agencies make arrests for drug crimes occurring on and off school grounds.