Dissertation (MA Education)This study aimed to explore the influence of language code-switching in the learning of the History subject in Tanzanian secondary schools in Mkalama district, Singida. This study was guided by the Socio-cultural theory of Vygotsky (1978). Vygotsky is best known for being an educational psychologist with a socio-cultural theory. Qualitative research approach and multiple-case design were used to collect, analyze and data presentation. Data were analyzed to provide teachers‟ and students‟ perceptions on the use of language code-switching when learning the History subject. The objectives of the study were to assess teachers‟ and students‟ perceptions on influence of language code-switching in the learning of History subject, to examine the types of code-switching in the learning of History subject among teachers and students in Tanzania secondary schools and to examine strategies that teachers and students employ to code-switching when teaching and learning of the History subject. The findings indicated that to a great extent, English as the language of instruction and examinable language in learning History subject in secondary schools is not well mastered. Also, code-switching has been viewed as an unavoidable strategy to support the leaner acquisition of History skills. Noteworthy, language code-switching has created lack of confidence in speaking, insufficient mastery of History skills. Furthermore, the study has explored strategies used by teachers and students to code switch when leaning the History subject. The study recommended that teaching of History subject by the use of language code-switching has to consider the types of language code-switching in relation to the nature of the topic, context and level of learner’s language ability. Also, more research has to be carried out on the influence of multilingual learning of History subject in Tanzania secondary school