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Testing the effectiveness of multisystemic therapy for young people with problem sexual behaviour.

Project Description

Adolescents account for about 20% of all sexual offences, but despite the social, psychological, and economic costs of juvenile sexual offending, few empirically validated interventions aimed at young people with problem sexual behaviour (PSB) exist. Multisystemic therapy for problem sexual behaviours (MST-PSB), a family-based intervention for problematic sexual behaviour, has been shown to be effective with this cohort of young people outside the UK.

In the USA, multisystemic therapy (MST) has been supporting families for the last 25 years with young people who are considered as being ‘high risk’ of out-of-home placements, such as foster care and custody. The Services for Teens Engaging in Problem Sexual Behaviour (STEPS-B) trial aimed to assess the feasibility of implementing MST-PSB in a UK setting.

MST is an intensive clinical treatment programme which aims to involve all environmental factors which affect juvenile offending, including family, school, and the community. MST-PSB is an adaptation of MST aimed at adolescents who have engaged in problematic sexual behaviours and often demonstrated other problem behaviours. It is an intensive family- and home-based intervention uniquely developed to address the multiple determinants of problematic sexual behaviour in adolescents. MST-PSB is designed to reduce problematic sexual behaviours; antisocial behaviours, and out-of-home placements.

Research outside of the UK has shown that young people who received MST-PSB were less likely to engage in problem sexual behaviour, to be rearrested for both sexual and nonsexual offences and spend less time in and out of home placements and confined facilities, in comparison to young people who received other community services (management as usual). The STEPS-B project was part of a £4.1m Scaling Evidence-based Interventions grant to the National Implementation Service to increase the use of five evidence-based interventions in children’s services: KEEP, RESuLT, STEPS-B, MST-FIT and AdOpt.


The DfE-funded independent evaluation published in 2017 was unable to reach firm conclusions due to the low number of families who were recruited, resulting in limited statistical analyses comparing MST-PSB to management as usual. Examining the effect sizes of the pre-post analyses of the secondary outcomes suggests that MST would likely have shown significant improvements in parental involvement and the degree to which family members felt connected to each other and supported. The evaluation identified the importance of the positive therapist relationship that enabled parents to understand a child’s behaviour and repair their relationship.

Lead Organisation

National Implementation Service


Anna Freud National Centre for Children and Families






Funding Information

Funding theme: Rethinking support for adolescents

Total amount awarded


Round 1 Jan 2015