Strong signals that prevention is a science growing in confidence, and that it needs to look less to medicine for a coherent treatment model were explained to key figures in the UK children’s services community by a leading US thinker on anti-social behavior, last night. “Too often we are urged towards a medical model, of diagnosing the ‘disease’ and treating it,” Professor Tom Dishion said. “I’m not sure that child and adolescent development in the context of family life is like that. It's more a case of health maintenance. It's like dental care. We all need a check-up and a little bit of help every now and then. I like to talk about health maintenance rather than the medical model.” Best known for his explanations of how adolescent peer groups escalate anti-social behavior, Tom Dishion is Director of the Child and Family Center at the University of Oregon. He was speaking in London last night at the annual lecture organized by the UK service design and prevention policy implementation organization Dartington-i.His theme was interventions that target the ecology of children’s lives – family, community and school – and the motivation for change that they are capable of generating and maintaining.“Ninety percent of people who quit smoking quit on their own,” he said. “They don't use a treatment program. If you watch what they do, you find they go through stages of pre-contemplation, contemplation, preparation and then action - and after that maintenance. Too many treatment programs start with action, but there are those three steps before that for most people who manage to change by themselves."For Dishion, tapping into a child or parent’s determination to change is fundamental to effective interventions. That connection is usually represented in programs that include simple and short involvements with families in familiar contexts.Service design is based on two robust theories. The family coercion model explains one link between parenting and anti-social behavior. A child does something wrong, the parent chastizes; the child likes the attention so does something worse. The parent shouts at the child, not realizing he is contributing to the escalation of the behavior. Parents can be taught to recognize and manage this phenomenon.Another foundation of Tom Dishion’s work is peer contagion. Adolescents who behave badly are drawn to each other. In their interactions they “talk up” antisocial conduct, reinforcing and escalating the behavior. Placing adolescents in unsupervised groups is self-defeating by this calculation.