Dissertation (MA Education)This study assessed the impact of School-Based In-service education and training on teacher’s competence to support learners to acquire the intended competences in primary schools in Magu District. The study was underpinned by constructivist curriculum theory and outcome based evaluation model. The study sought to achieve three objectives: assessing and critically analysing the strengths and limitations of school-based INSET program, determining the behavioural changes among beneficiaries of school-based INSET program and determining the success factors of the program. Sixty (60) respondents were randomly and purposively sampled including 1 District Academic Officer (DAO), 1 school inspector, 2 Ward Education Officers (WEO), 5 Head teachers, 1 TRC Coordinator and 50 primary school teachers. The data were gathered through structured interview, questionnaire, observation and documentary analysis where qualitative data were coded, categorized and organized into thematic and the quantitative data were analyzed using percentage, frequencies, means and standard deviation. The key findings of the study indicate that teacher’s competence on classroom management practice was significantly improved after attending the school-based INSET program. This was signified with teacher’s awareness of the LCA and ability in preparation of scheme of work, lesson plan and lesson notes. On the other side, the findings point out the low ability of teachers in preparation of teaching and learning materials. However, the findings suggest that the program could be successfully implemented with improvement on financial management mechanism, accreditation system and time schedule. Therefore, it can be concluded that school-based INSET is a suitable model for improving teacher’s competence in primary schools as it can cover large population with minimum costs.