The book is about an empirical study carried out in Nairobi County in Kenya in the year 2011.The study is about Kiswahili performance in public day secondary schools. The author of the book sought to find out the factors that determine performance in Kiswahili in public day secondary schools. The findings of the study revealed that the age of the students, home enviroment of the learner, instructional materials,enhancing Kiswahili teachers skills,instructional techniques and use of other languages were some of the factors that determined performance in Kiswahili. The author collected data from nine public day secondary schools in Nairobi county. They included four mixed public day secondary schools, three boys only public day secondary schools and two girls only public day secondary schools.