The aim of this paper is to examine the relationship between provision of sufficient physical and human resources and academic performance in primary schools. The paper is based on a study conducted in Central Nyanza Region, in the Counties of Siaya and Kisumu. The study employed the mixed methods approach and was conducted using descriptive survey design. The instruments used to collect data included questionnaire, interview guides and observation checklist. The sample was selected using stratified and simple random sampling. Data was collected from 136 schools where 136 head teachers and 493 teachers were respondents¬¬¬¬. The researcher interviewed 36 teachers. The unit of analysis was primary schools. The data was analysed using descriptive and inferential statistics. Descriptive statistics, such as measures of central tendency and percentages, were used to analyse the data. Eta square was used to test the hypothesis. The level of significance was 50%. It was established from the study findings that school-related factors such as poor condition of physical facilities such as classes, inadequate teachers, inadequate text books, poor supervision of teaching/learning process contributed to the poor schools’ achievement in Central Nyanza region. It was thus recommended that schools should be provided with all resources required for curriculum implementation such as adequate teachers, classrooms, text books and exercise books. Moreover, head teachers should adequately supervise teaching/learning in their schools. They should ensure that teachers and pupil absenteeism are reduced to the minimum.