Education is important for human development. It is a basic human right as articulated in the Constitution of United Republic of Tanzania of 1977. Since then, a series of reforms for improving access, quality and relevant education were adopted in the country. This study evaluates the relevance and quality of social science textbooks used in primary education. The study critically reviews primary education social sciences books. I argue that there were varieties of social studies textbooks and supplementary books used in primary education. These textbooks vary in terms of content, illustration, language and methodology. There is no harmony of content, while some textbooks had wrong contents altogether. Although teachers and learners benefited from using these textbooks, lack of content harmonisation deterred the effectiveness of achieving instructional and national objectives. The study recommends that a review and harmonisation of textbooks be undertaken, in order to attain the required national agenda.