Young people with learning needs are more likely to become involved in anti-social behaviour than young people without learning needs (Emerson et al, 2011). Reasons for this are complex and not well understood, but one contributing factor is that young people with learning needs are unlikely to be recognised and supported in services (Hall, 2000). Lack of recognition and support is also present for parents with learning needs (Emerson, 2011). These families benefit from interventions that include wider systems (Tausendfreund et al, 2016). Multisystemic Therapy (MST) has been shown to be an effective systemic intervention for this group (Butler et al, 2011). An enhancement for young people with Intellectual Disabilities (MST-ID) has recently been developed in the Netherlands (Blankestein et al, 2019), but MST-ID has not been adopted in UK settings. Qualitative grounded theory methodology was used to explore young peoples’, caregivers’, and therapists’ experience of MST where the young person or caregiver has learning needs, to understand the mechanisms and barriers of engagement and change and how they fit with the standard MST theory of change (Hennegeler et al, 2002). Semi-structured interviews were conducted with ten participants: two young people, three caregivers, and five therapists, recruited from MST teams across the UK. Seven theoretical codes were developed from the data: families’ relationship to help, routes to engagement, empowering families, improving family functioning, mobilising the wider ecology, adapting communication, and adapting timings. The mechanisms of engagement and change largely mirrored the existing MST model of change, with extra emphasis required in empowering families, improving family functioning, and mobilising the wider ecology. Adapting communication and timings were found to be unique adjustments for families with learning needs. This study found that these adjustments were successfully implemented in standard MST. Further research would help understand the impact of the enhancements in MST-ID and how this compares with standard MST. This study recommends specialist training for therapists working with people with ID.