This article introduces and analyzes a Walrasian model of worker flows, job flows, vacancies, and unemployment. Calibrating the model to U.S. data, the article finds that all variables comove with output quite well but that they fluctuate too little. However, the failure is not as bad as in “Shimer's puzzle.” Interestingly, the article also finds that introducing establishment dynamics into the model, while realistic, is irrelevant for understanding unemployment and vacancy fluctuations: The business cycles of the model with establishment dynamics are virtually the same as those of a version with a representative firm.