Stalking has become an increasingly common problem in the criminal justice system, with inconsistent and incomplete solutions for dealing with offenders and protecting victims. Stalking is generally defined as repeated engagement in behaviours that are deliberate, unwanted, and result in the victim feeling harassed, alarmed, or fearful for their safety. However, the actual behaviours an offender may engage in can be diverse and are often not inherently in violation of the law. Despite descriptions of stalking behaviour dating back to the Roman Empire, the variety of behaviours that may comprise stalking continues to grow with social and technological advances. Underlying the diverse behaviours that may qualify as stalking is a quite heterogeneous group of offenders. Theoretical explanations for stalking have focused primarily on problematic personality traits and psychotic symptoms, and these models have given rise to several typologies that characterise different subgroups of stalking offenders. The incidence of violence in stalking cases has also received considerable attention, and several risk factors for identifying offenders who are prone to violence and stalking recidivism have been proposed.A prior intimate relationship between offender and victim has emerged as one of the most important risk factors, as has the presence of threats, a history of substance abuse, and a diagnosis of antisocial personality disorder. Despite consistent evidence of negative outcomes for both stalking offenders and victims, few treatment interventions have been developed and for those that have, findings have been mixed.