In Tanzania, for a number of years, secondary school students, parents and other Education stakeholders have been questioning the essence of having a foreign language as both; a medium of instruction and an academic subject in secondary schools. This paper focuses on finding out the performance of students in English as an academic subject based on the first semester English examination results among form four students from the selected schools, as well as examining factors behind their performance. Data obtained from Questionnaire were analyzed through SPSS. Ten (10) community based secondary schools in Dodoma Municipality where picked through systematic random sampling to represent other schools of the same caliber in Tanzania. In line with this, 150 students in a proportion of 15 students from each school were picked as respondents for this study through systematic random sampling as these were those identified first to have the same results above. The study found out that the performance of students in English as an academic subject in the community based secondary schools is below average and this is contributed by a number of factors such as the method and practice of teaching and learning as well as students’ background knowledge and attitude.