Today we know much more about the effects of pretrial detention than we did even five years ago. Multiple empirical studies have emerged that shed new light on the far-reaching impacts of bail decisions made at the earliest stages of the criminal adjudication process. The takeaway from this new generation of studies is that pretrial detention has substantial downstream effects on both the operation of the criminal justice system and on defendants themselves, causally increasing the likelihood of a conviction, the severity of the sentence, and, in some jurisdictions, defendants’ likelihood of future contact with the criminal justice system. Detention also reduces future employment and access to social safety nets. This growing evidence of pretrial detention’s high costs should give impetus to reform efforts that increase due process protections to ensure detention is limited to only those situations where it is truly necessary and identify alternatives to detention that can better promote court appearance and public safety.