The study covered factors affecting performance of Kenya Certificate of Primary Education in Kirinyaga West District, in Kenya. It examined school management practices; teaching and learning resources available; teacher-pupil ratio; syllabus coverage and factors with direct bearing on pupils’ academic performance. The study was conducted in twelve public primary schools in Kirinyaga West District. Survey research design was used. Data was collected using questionnaires, document analysis, interviews and discussions. It was analyzed using descriptive statistics and presented in tables, pie charts and bar graphs. The study found out that teaching and learning materials were not adequate,school management practices were insufficient, coverage of syllabus was not thorough and lack of capacity among school management was also a challenge. The study recommended more teaching and learning resources be provided, employment of additional teachers, capacity building of school management be enhanced, supervision of school be intensified and parents be fully involved in educational projects and programmes.