Objective: In guilty plea hearings, judges must determine whether defendants’ plea decisions were made knowingly, intelligently, and voluntarily. Little is known, however, about how plea hearings unfold, especially in juvenile court, where hearings are generally closed to the public. In this study, we had the unique opportunity to systematically observe plea hearings in juvenile and criminal court. Hypotheses: We predicted that plea hearings would be brief and that defendant participation, especially among juveniles, would be minimal. We also explored how often judges addressed the plea validity components of knowingness, intelligence, and voluntariness and whether addressing these components differed by the type of court (juvenile, criminal), pretrial custody status, and pled-to charge severity. Method: Trained coders in California (n = 104, juvenile court) and Virginia (n = 140, juvenile court; n = 593, criminal court) systematically observed more than 800 guilty plea hearings. Coders reliably documented hearing length, whether the defendant was in pretrial custody, whether the evidence was reviewed, details on defendant participation, and judicial attention to plea validity. Results: On average, juvenile plea hearings lasted about 7 min and criminal plea hearings lasted 13 min. Prosecutors rarely reviewed evidence against the defendants in the juvenile courts, and in one juvenile court, judges paid virtually no attention to plea validity. In the other two courts, certain waived rights (e.g., to trial, to silence) were reviewed consistently. Depending on the court, hearing length and plea validity elements addressed varied by defendants’ prehearing custody status and the pled-to charge severity. Conclusions: These findings provide novel insight into how components necessary for plea admissibility—knowingness, voluntariness, and intelligence—are discussed with defendants and, in doing so, raise concerns about the degree to which plea validity is actively assessed in plea hearings. Plea hearings are formal, minutes-long events in which defendant engagement is low. (PsycInfo Database Record (c) 2022 APA, all rights reserved)