This article, drawing on a set of studies conducted in the framework of the Language of Instruction in Tanzania and South Africa (LOITASA) research project, shows how well African students express themselves if they are allowed to use a familiar African language, and conversely the difficulties they have when forced to use a foreign language, a language they hardly hear and never use outside of school, as a language of instruction. A key finding of the research is that when the foreign language, English in this case, is used, there is a much larger spread in test performance between students. This means that a small group of students succeed while the vast majority sinks. The author therefore argues for working towards a goal whereby African children like children in industrialized countries may study in their own language. Pursuing this goal should be a centrepiece in poverty reduction strategies.