Adverse childhood experiences (ACEs) are linked to both poor mental health and adverse social outcomes, including arrest and incarceration. Furthermore, individuals with serious mental illnesses (SMI) are known to have high rates of childhood adversity and are overrepresented in all facets of the criminal justice system. Few studies have examined the associations between ACEs and arrests among individuals with SMI. We examined the impact of ACEs on arrest among individuals with SMI while controlling for age, gender, race, and educational attainment. In a combined sample from two separate studies in different settings (N = 539), we hypothesized that ACE scores would be associated with prior arrest, as well as rate of arrests. The prevalence of prior arrest was very high (415, 77.3%) and was predicted by male gender, African American race, lower educational attainment, and mood disorder diagnosis. Arrest rate (number of arrests per decade, which thus accounted for age) was predicted by lower educational attainment and higher ACE score. Diverse clinical and policy implications include improving educational outcomes for individuals with SMI, reducing and addressing childhood maltreatment and other forms of childhood or adolescent adversity, and clinical approaches that help clients reduce the likelihood of arrest while addressing trauma histories.