This paper examines the effects of pretrial detention on case outcomes in federal criminal cases. Unlike cash-bail regimes that are prevalent in state courts, federal courts rarely use money bail as a condition of pretrial release. Nonetheless, this paper documents significant effects of pretrial detention for federal criminal defendants. Using data spanning 71 federal district courts, I present evidence that pretrial release reduces a defendant’s sentence increases the probability that they will receive a sentence below the recommended sentencing range. Pretrial release also appears to lessen the probability that a defendant will receive a mandatory minimum sentence when one is charged, but does not seem to affect the probability of facing a mandatory minimum. To address the identification problem inherent in using pretrial detention status as an explanatory variable, I exploit variation in magistrate judges’ propensities to release defendants pending trial, which allows magistrate judge leniency to serve as an instrumental variable for pretrial release. The paper also provides evidence that pretrial release affects case outcomes through two channels: first, by giving defendants the opportunity to present mitigating evidence at sentencing and second, by making it easier for defendants to earn a sentencing reduction by providing assistance to the government.