Prosecutors have considerable discretion over defendant outcomes in criminal courts and aim to apply their discretion to reserve incarceration for those who are more likely to re-offend. However, it is unclear whether they have accurate beliefs about the correlates of re-offense. In a survey of over 100 prosecutors in North Carolina, we find that prosecutors have systematically biased beliefs about how age and prior criminal history relate to re-offense. Prosecutors underestimate the likelihood of criminal re-offense among young offenders and overestimate the likelihood of criminal re-offense among those with long criminal histories. In future work, we will link these beliefs and the extent of each prosecutor’s inaccuracies to court records to investigate how prosecutors’ beliefs relate to the outcomes in their cases.