Accessible summary Services should give support to the whole family who live with a child with a learning disability. The aim of this study was to understand how helpful a family support service is in reducing challenging behaviour in children with learning disabilities. We did this by looking at the outcome measures they already use. We wanted to find out how good they are at measuring change. We found that The Family Intensive Support Service (FISS) reduced challenging behaviour in children and increased parent's ability to cope with and manage challenging behaviour. Outcome measures used by the FISS team were good at showing change. Summary Seven per cent of individuals with learning disabilities also display challenging behaviour (Challenging behaviour: analysis and intervention in people with severe intellectual disabilities, 2001, Cambridge, Cambridge University Press), which has an effect on the whole family. Services need to be developed to support and reflect this need (Better health, better lives: children and young people with intellectual disabilities and their families, 2010, Romania, Bucherest). This is a retrospective pre‐ and postevaluation study examining the utility of specific outcome measures assessing the effectiveness of interventions addressing behavioural problems within a Family Intensive Support Service (FISS). After one year, FISS successfully reduced problematic behaviours and increased a sense of coping and ability to manage the behaviour for parents. The outcome measures used were sensitive enough to show change on specific subscales of the measure. Further research is needed to look at whether there is a need to create a new measure encapsulating the best elements of these measures.