Issues of technique in work with adolescents who, if adult, would attract a forensic label, are discussed with especial focus on interpretation and countertransference in the light of primitive anxieties and body-based mechanisms of defence. The therapist as ‘new object’ and ‘developmental object’ is explored. The case study of Matthew — a mid-adolescent who has abused a younger child, is delinquent, seeks violent and dangerous situations and experiences outbursts of aggression — is used as illustration throughout.