Objective: Research suggests distinct criminal risk factors, not mental illness, are more strongly associated with most criminal behaviors. This notion has been supported among inpatient persons with mental illness (PMI) when examining antisocial cognitions; however, other key criminogenic risk factors (the Big Four and Central Eight risk factors) have not been examined among psychiatric inpatient PMI. Hypotheses: We hypothesized that criminal justice (CJ)-involved PMI would endorse significantly greater criminogenic risk compared to non-CJ-involved PMI and that these risk factors would significantly and accurately identify whether PMI had CJ involvement. Additionally, we hypothesized that PMI with and without a history of CJ involvement would not significantly differ on their reported psychiatric symptomatology. Method: We examined all Central Eight criminal risk factors and psychiatric symptomatology among psychiatric inpatient PMI (N = 142) with (n = 74) and without (n = 68) CJ involvement histories. Results: Multivariate analysis of variance and discriminant function analysis indicated significant differences between the Big Four and Central Eight criminal risk factors when classifying CJ and non-CJ groups. The Big Four risk factors correctly classified 85.9% of participants, and the Central Eight correctly classified 99.3% of participants into CJ and non-CJ groups; however, psychiatric symptoms only correctly classified 57.7% of participants into CJ and non-CJ groups. Conclusions: Criminal risk factors appear to be more strongly associated with CJ involvement among PMI than psychiatric symptomatology; therefore, psychotherapeutic intervention on criminal risk factors, not only mental illness, may decrease criminal recidivism among CJ-involved PMI. Public Significance Statement People have often assumed persons with mental illness become criminal justice involved because of symptoms associated with their illness or lack of mental health treatment; however, criminal risk factors (the Big Four and Central Eight), not severity of psychiatric symptomatology, most accurately classified psychiatric inpatients with and without a history of criminal justice involvement. Thus, psychotherapeutic interventions should target criminal risk factors, such as antisocial personality, attitudes toward criminal associates, and job-seeking behavior. In other words, to be most successful, when treating criminal justice-involved persons with mental illness, practitioners should assess and treat not only symptoms associated with their mental illness but their criminal risk as well.