In misdemeanor cases, pretrial detention poses a particular problem because it may induce innocent defendants to plead guilty in order to exit jail, potentially creating widespread error in case adjudication. While practitioners have long recognized this possibility, empirical evidence on the downstream impacts of pretrial detention on misdemeanor defendants and their cases remains limited. This Article uses detailed data on hundreds of thousands of misdemeanor cases resolved in Harris County, Texas—the third-largest county in the United States—to measure the effects of pretrial detention on case outcomes and future crime. We find that detained defendants are 25% more likely than similarly situated releasees to plead guilty, are 43% more likely to be sentenced to jail, and receive jail sentences that are more than twice as long on average. Furthermore, those detained pretrial are more likely to commit future crimes, which suggests that detention may have a criminogenic effect. These differences persist even after fully controlling for the initial bail amount, offense, demographic information, and criminal history characteristics. Use of more limited sets of controls, as in prior research, overstates the adverse impacts of detention. A quasi-experimental analysis based on case timing confirms that these differences likely reflect the causal effect of detention. These results raise important constitutional questions and suggest that Harris County could save millions of dollars per year, increase public safety, and reduce wrongful convictions with better pretrial release policy.