This study attempts to answer the question of why some children fail while others succeed in the first year of school when they appear to have at least average abilities and to come from family environments which seem, on the surface at least, to provide similar developmental opportunities. The researcher observed in ten, four-year-old children's homes over a period of four days for each child and followed these intensive home observations with three-monthly, informal interviews with adult family members. Each child was observed in school intensively, on entry to school and every three months following entry until six years of age. Informal interviews were conducted with the class teachers every three months. During the 'intensive' home and school observations continuous hand-written narrative recordings of natural communication incidents were made of all the oral language and activities of the focal child, and of the language and activities of other children and adults when what they said and did was in the vicinity of the focal child. Notes were made of the location, atmosphere, body language, people present, and focal objects throughout the time of the observations. Field notes were made each night after every home, school or pre-school visit. Each child was tested with a battery of tests on entry into school at five years, at five-and-a-half years and at six years. The gathering of these different data meant a wide variety of information about the child's total ecological environment was gathered. A variety of ways for examining the data for a relationship between the behaviours and social experience of the child which occurred at home and measures of achievement in school were explored. These included a variety of language variables (e. g. exposure to question types, statement types, amount of talk) and measures of variables related to socia-economic status and home environmental factors (e.g. the HOME Scale, Caldwell & Bradley, 1979). Al though some of these variables were significantly correlated with school achievement, it was not clear that the problem of why some children succeeded in school while others failed had been satisfactorily solved. A more detailed analysis of the data was carried out which differed from most other psychological or educational studies in that it focused on the underlying structures of the natural socio-linguistic patterns of interaction in both home and school first year classrooms. The task was to describe observable social interaction in terms of the underlying structures which characterised the home subcultural experience of the children and the sub-cultural learning (acculturation) required of the children in order to successfully adapt to the school environment. The theory generated to explain this complex problem was adapted from a theory sometimes termed script theory, or schema theory. It was developed into a framework which could deal with both children's present school experience and the children's past experience of the structure of meaningful social interactions. The results showed that the underlying structure of patterns of interaction (schema) which the children brought with them from home to school did indeed cause failure for some children at school. The children's experience of patterns of interaction in the homes which were like school patterns of interaction correlated 0.91 with achievement in school. The greater the variety of school-like patterns of interaction occurring in the homes the greater a child's achievement rate was likely to be. This study has implications for classroom organisation, for the structure of classroom patterns of interaction and for young people who come from home ecological environments which are significantly different from the present classroom environment. It is argued that children are our nation's most important resource and we need to examine with great care what we are doing to promote alternative classroom environments.