The purpose of this study was to investigate the effects of school-based factors on the academic
performance of students in mathematics in public secondary schools in Kibera Sub-County, Nairobi
County, Kenya. The study was guided by the following objectives: to examine the availability of
teaching and learning resources for learners in public secondary schools; to explore how students’
level of engagement affects learners’ academic performance in mathematics in public secondary
schools; to determine the effects of school culture on student’s academic performance in mathematics
in public secondary schools in Kibera Sub-County, Nairobi County. The study was anchored in the
Social Cognitive Theory. A descriptive survey research design was employed, and a quantitative
approach was used for data analysis. The study was conducted in three public secondary schools in
Kibera Sub-County: one Boys' secondary school, one Girls' secondary school, and one Mixed
secondary school. The research sample included 90 student participants from the three schools and 9
Mathematics teachers. A simple random sampling method was used for data collection. Data
collection was organized and analyzed using Statistical Package for the Social Sciences (SPSS)
version 28, with results presented through pie charts, frequency tables, and graphs. The study findings
revealed that a significant shortage of essential learning materials, such as textbooks, mathematics
laboratories, and ICT tools, negatively impacted mathematics performance. Student engagement was
generally moderate, but inconsistent homework completion and low participation in extra revision
activities were noted. School culture showed some positive elements, such as teacher support for daily
practice, but lacked organized extracurricular mathematical activities and peer encouragement. The
study concluded that the combined impact of inadequate resources, low student engagement, and
weak school culture created an environment that hindered effective learning. Recommendations were
made for students, teachers, schools, and the Ministry of Education to address these issues, including
enhancing resource provision, promoting collaborative learning, encouraging innovative teaching
methods, and fostering a more supportive school culture for mathematics learning. However,
addressing challenges such as limited resources, time management, and certain teaching methods is
crucial. Improving the availability of textbooks, internet access, and other teaching materials, along
with adopting a more interactive and student-centred approach in mathematics, will significantly
enhance the academic performance of students in mathematics.