Early intervention for children with behavioural difficulties can be effective in terms of outcomes for both the children and their families. Early intervention can save a child from long-term outcomes such as school failure, peer rejection and later offending. However, in terms of accurate assessment of young children's behavioural difficulties, there is disparity between what the research suggests as best practice and what actually occurs in kindergartens and schools. This paper challenges current thinking about the timing of behavioural assessments for young children and describes the elements of an effective screening procedure for these children. The authors' own behaviour screening tool is described. The implications of screening young children for behavioural difficulties are discussed, as is teachers' reluctance to do this. (Contains 2 tables.)