Abstract: Misdemeanor convictions are typically dismissed as low-level events that do not deserve the attention or due process accorded to felonies. And yet with ten million petty cases filed every year, the vast majority of U.S. convictions are misdemeanors. In comparison to felony adjudication, misdemeanor processing is largely informal and deregulated, characterized by high-volume arrests, weak prosecutorial screening, an impoverished defense bar, and high plea rates. Together, these engines generate convictions in bulk, often without meaningful scrutiny of whether those convictions are supported by evidence. Indeed, innocent misdemeanants routinely plead guilty to get out of jail because they cannot afford bail. The consequences of these convictions are significant: in addition to the stigma of a criminal record, misdemeanants are often heavily fined, incarcerated, and/or lose jobs, housing, and educational opportunities. In other words, petty convictions are growing more frequent and burdensome even as we devote fewer institutional resources to ensuring their validity. The misdemeanor phenomenon has profound systemic implications. It invites skepticism about whether thousands of individual misdemeanants are actually guilty. It reveals an important structural feature of the criminal system: that due process and rule-of-law wane at the bottom of the penal pyramid where offenses are pettiest and defendants are poorest. And it is a key ingredient in the racialization of crime, because misdemeanor processing is the mechanism by which poor defendants of color are swept up into the criminal system, i.e., “criminalized,” with little or no regard for their actual guilt. In sum, the misdemeanor process is an institutional gateway that explains many of the criminal system’s dynamics and dysfunctions.