This thesis contains three related studies in the general field of educational psychology and in the specific area of behaviour, educational achievement and educational needs in mainstream schooling. The work investigated relationships between behaviour and achievement in the educational context of Kuwait, where poor behaviour has been argued to be a primary cause of low education achievement levels. Using a systemic approach, the first study sought to establish patterns of behaviour and educational achievement among Kuwaiti pupils in grades 4 and 5 of primary schools. The results indicated associations between some behavioural traits (particularly hyperactivity) and measures of literacy and numeracy. The second study took advantage of an inclusion project undertaken in Kuwait to improve classroom management practices and increase awareness of, and support for, students with learning problems. Using the same methods as in Study 1, the second study investigated levels of behaviour and educational achievement among pupils in grades 4 and 5 taught by teachers who had been inclusion trained in comparison with non-inclusion trained teachers in an adjacent educational district. Results suggested that the hypothesised associations between behaviour and academic attainment existed but there were no significant differences in the measures between schools where teachers had been inclusion trained and those where they had not. Thus, relations between behaviour and academic achievement are important and may be impervious to change. The third study explored the comparative attitudes, practices and beliefs of inclusion and non-inclusion trained teachers and identified one significant difference, which was in terms of the educational structures of Kuwait. The thesis has the potential to make contributions to knowledge in several areas, both theoretical and practical. One is that there is a relative lack of similar studies that are set within a Middle Eastern context generally and within a Kuwaiti context specifically. Others include a systemic approach (something that differentiates it from a majority of work in this area of educational psychology) and the potential to inform future policies and interventions in Kuwaiti primary schools that are focused on behaviour and its associations with academic attainment.