The study investigates the effects of the language of the catchment area on learning Kiswahili in Kapseret division, Kenya, finding that Nandi is the predominant local language, yet Kiswahili is often used for communication. It reveals that while learners do not frequently use the local language at school, its absence negatively impacts their performance in Kiswahili due to issues such as direct translation from mother tongue and stigmatization of Kiswahili. Recommendations include increasing parental awareness to foster a positive attitude towards Kiswahili to improve learning outcomes.