Violent offender interventions are still more intuitively than empirically driven. The most important goal of interventions with violent offenders is to reduce reoffending risk. This chapter provides general principles of intervention for violent offenders: the risk principle, risk and treatment intensity; criminogenic needs; and responsivity issues. It then considers how to judge whether programme evaluation designs are effective or not, and then discusses two types of programmes: low-intensity anger management programmes and high-intensity multifactorial programmes. Positive psychology approaches such as Good Lives model (GLM) provide an important humanistic counterweight to pressure on some programmes to integrate politically driven punitive agendas into their practices. The chapter also presents a case example of violent offender intervention: the Rimutaka Violence Prevention Programme (RVPU), which is a ten-year-old thirty-bed medium-secure unit in a large prison near Wellington, New Zealand.