Self-report data have consistently demonstrated acceptable reliability and validity in prior studies by exhibiting high correlations with other criterion related measures of criminal frequency and arrest history. Mental health factors and substance abuse factors are suspected to affect the quality and accuracy of self-reported data. This analysis sought to examine the impact of major mental illness and substance abuse factors on the validity of self-reported criminal history data as given by clients of a psychiatric probation and parole service. After controlling for socio-demographic variables, the number of officially recorded arrests, high number of lifetime hospitalizations and overall years spent in jail significantly explained the number of self-reported arrests. The predominance of the official record in explaining self-reported arrest history suggests that self-reported arrest history data given by a psychiatric offender population is as valid as that given by general offender populations. Substance abuse factors and mental illness factors did not affect the quality and accuracy of self-reported arrest history.