Since the inception of the federal sentencing guidelines, scholars and practitioners alike have debated the ability of the guidelines to produce uniformity, consistency, and fairness in sentencing. Congress believed that constraining judicial discretion would ameliorate extra-legal disparities in sentencing practices. Twenty-five years after implementation, however, arguments are that guidelines have only displaced discretionary power to earlier stages in the sentencing process where extra-legal disparities may be obscured from final sentencing statistics. To date, the majority of sentencing research has focused on the final judicial sentence and far fewer studies have examined data regarding decision-making stages that precede the incarceration and sentence length decisions. We therefore have an incomplete picture of the nature of sentencing practices with regard to the extent, and sources, of extra-legal disparities. The current study explores inter-district variation in the sentencing of federal narcotics offenders by examining prosecutorial decisions to grant substantial assistance departures employing district-specific analyses. The findings highlight substantial inter-district disparity in the use of these departures, and reveal how racial/ethnic and gender disparities can be produced at earlier stages of the federal sentencing process via prosecutorial decisions such as those for substantial assistance departures.