Scallywags is a community-based, early intervention programme for young children (aged 3-7) with behavioural, emotional and social problems, which integrates work in the home and school with a parenting curriculum and direct work with children. A pre-post intervention study across multi-sites of 340 participants is reported. Using standardised measures, the study found statistically significant reductions in problems at home and school experienced by children who completed the programme, and in parental stress levels. Participation was found to be high and the project acceptable to parents, many of whom would be described as hard to reach. The rigorous evaluation of this real-life service and its positive outcomes highlight the potential of such programmes to tackle the needs of these children and families, and help prevent longer-term problems associated with early onset behavioural problems, including social exclusion, antisocial behaviour and educational failure. Population characteristics of the sample are appended. (Contains 5 figures and 1 table.)