This chapter provides the risk assessment in forensic psychiatry, and considers the legal aspects of crime and mental illness. Three types of research methodologies have been used to examine the relationship between violence and psychosis: prevalence of violence among those with a diagnosis of schizophrenia; prevalence of schizophrenia among those convicted of violence; and the prevalence of violence among those with and without schizophrenia. Most studies that look at the link between major mental disorders and violence have focused on those with schizophrenia. Almost 80% of remand prisoners in England and Wales were found to have at least one personality disorder, with antisocial personality disorder (APD) being most prevalent. Assessment of the risk of harm to others posed by those with mental illness has become an increasingly important part of clinical practice in psychiatry, particularly forensic psychiatry.