Socialization agents shape pupils' behaviour. Pupils' behaviour has deteriorated over time in primary schools in Kenya. The purpose of the study was to contextualise the influence of socialization agents in shaping primary school pupils in Thika Sub County. The objective of the study was to assess the role of school variables in shaping pupils' behaviour. Descriptive research design was applied with a target population comprising of 570 teachers, 3256 pupils and 69 head teachers. The sample size consisted of 57 teachers, 325 class seven pupils and 7 school heads. The research instruments used consisted of the teachers and pupils questionnaire and an interview guide for head teachers and sub county director of education. The research instruments were piloted and a correlation coefficient of < 0.7 was acceptable. Data was analyzed using both descriptive and inferential statistics with the aid of the Scientific Package for Social Sciences (SPSS). The study established that the school rules played a key role in management of children's behaviour in school since they maintained socially acceptable norms within the school. However the school rules did not dictated the form of punishment for non-compliance. The school should carry out background checks on learners in order to establish behavioural issues that are likely to face from a particular set of learners. This would assist in discipline management in schools. The teachers should also consider prior behavioural and discipline issues in order to determine how to address the current pupils' indiscipline. The school administrators should ensure that the school rules specify the punishment for various issues of nonadherence to the rules. This would assist in having uniform forms of punishment and thus learners would understand the punishments and the role of punishment in shaping their behaviour.