Our criminal justice system resolves most of its cases through plea bargains. Yet the U.S. Supreme Court has not required that any evidence, even exculpatory or impeachment evidence, be provided to the defense before a guilty plea. As a result, state rules on pre-plea discovery differ widely. While some jurisdictions follow an “open-file” model, imposing relatively broad discovery obligations on prosecutors early in the criminal process, others follow a more restrictive, “closed-file” model and allow the prosecution to avoid production of critical evidence either entirely or until very near the time of trial. Though the advantages and disadvantages of both models are debated, surprisingly little is known about the models’ real-world operation. In this Article, we report the results of an original empirical study in which we surveyed practicing prosecutors and criminal defense attorneys about their pre-plea discovery practices. We surveyed attorneys from Virginia and North Carolina, two adjacent states, which are demographically and geographically similar, but have notably different discovery rules. North Carolina mandates open-file discovery early in the criminal process. By contrast, Virginia protects certain critical documents, such as witness statements and police reports, from discovery. Our findings indicate that, as expected, open-file discovery can promote more informed guilty pleas. It leads to improved pre-plea disclosure of most categories of evidence. The practice is also viewed as more efficient in that it reduces discovery disputes and speeds up case dispositions. We also found little evidence that open-file discovery endangers the safety of witnesses, a common argument against the practice. Open-file discovery does not, however, appear to enhance the disclosure of certain impeachment evidence, such as the prior convictions of prosecution witnesses. Further, practitioners reported that even when the entire case file is turned over to the defense pre-plea, the file is frequently missing some information relevant to the case. The Article interprets these findings and concludes with a general endorsement of the North Carolina open-file system over the Virginia closed-file system as a better guarantor of informed decisions and efficient process in criminal cases.