Prior to September 2023, Illinois’ pretrial system broadly resembled those in most other states. Following arrests, pretrial detention and release decisions were made at relatively brief and informal bond hearings. The outcome of most bond hearings was either a release (with or without conditions) or continued detention pending the posting of bond in an amount set by the judge. Pretrial detention under this system was routine, as was the requirement of money payments to secure release. The PFA, an ambitious set of pretrial reform measures that went into effect across Illinois on September 18, 2023, changed almost everything about this system. Most notably, the law makes Illinois the first state to abolish cash bail altogether. It requires pretrial release for most defendants, limiting the kinds of release conditions that can be imposed, and reserving detention only for cases involving the most serious kinds of charges. Even for those accused of detention-eligible offenses, pretrial detention under the PFA requires a special petition, a formal hearing, and clear and convincing proof that release would create a public safety or flight risk that cannot be mitigated by any available release conditions. These and other fundamental changes to traditional pretrial detention and release practice generated controversy when they were proposed, and have drawn widespread interest and attention now that they are being implemented. It is vital for the field and the public that the results of this ambitious experiment in pretrial reform be carefully assessed and reported.