In 2008, the U.S. had between 12 and 14 million ex-offenders of working age. Because a prison record or felony conviction greatly lowers ex-offenders’ prospects in the labor market, we estimate that this large population lowered the total male employment rate in 2008 by 1.5 to 1.7 percentage points. About one in seventeen adult men of working age was an ex-prisoner and about one in eight was an ex-felon. In the same year, we estimate that ex-offenders accounted for the loss of some 1.5 to 1.7 million workers from the U.S. economy. The rise in the ex-offender population overwhelmingly reflects draconian changes in the U.S. criminal justice system, not changes in underlying criminal activity. Dramatic increases in sentencing, especially for drug-related offenses, account for the mushrooming of the ex-offender population documented here. Since higher levels of incarceration are not the result of higher levels of crime, changes in sentencing today can greatly reduce the size of the ex-offender population in the future. In the absence of reform of the criminal justice system, ex-offenders in the working-age population will rise substantially in coming decades, increasing the employment and output losses.