The study aimed at establishing factors influencing the implementation of NFE in non formal schools of informal settlements of Mukuru Kwa Njenga, Nairobi Kenya. The study endeavoured to identify the challenges faced by NFE sector in non formal primary schools of Mukuru Kwa Njenga informal settlements. It also sought to establish the administrative challenges that head teachers face as result of lack of qualified and professional teachers, teacher turnover, teachers’ attitude towards NFE, inadequate physical facilities and inadequate of teaching/ learning resources. The study was based on A Theory of Change. The research design used in this study was descriptive survey. The target population was the NFSs of the informal settlements of Mukuru Kwa Njenga. The research instrument used was one set of questionnaire to the head teachers, teachers and students. In data collection twenty schools were used whereby one was used for piloting and nineteen for final study. The respondents were primary school heads of non formal schools, teachers and students of NFS. The data was analyzed using frequencies and percentages for easier interpretation.