Description: South Africa participated in the Progress in International Reading Study (PIRLS) for the first time in the PIRLS 2006. This was the most complex study conducted on reading literacy in South Africa to date. Whilst internationally in PIRLS most countries tested pupils at only one grade level, pupils in two grades were tested in South Africa. Children were assessed in all of the official 11 languages in more than 400 schools and children in both grade 4 and grade 5 were assessed the language of instruction they had received in grades 1-3. However, it should be said that this does not necessarily mean that all children have had the opportunity to learn in their home language and the extent to which this is the case will be explored in the PIRLS data. Nonetheless after four years of schooling, internationally children are expected to be able to read and now start the process of reading to learn. Initially, South African children start their learning at school in their home language and this practice continues until grade 3. However, in the majority of schools, the language of instruction changes and in grade 4 more than 80% of South African pupils learns in a second language. It is widely believed that the mixing of the languages of instruction is partly to blame for the continued underperformance in both primary and secondary school level of South African children, particularly in international studies (Howie, 2002). The authors want to ascertain to what extent are South African pupils proficient readers in their main language (or alternatively the language which they have received reading instruction in for four years) and secondly what progression is made after an additional year (i.e.: what value is added to that language) after the language switch. The South African situation is complex due to the fact that most white, Indian and coloured children will continue to receive their schooling in the same language of instruction from grade 1-12, whilst most children speaking African languages at home will switch at grade 4 to either English or Afrikaans despite the current government language policy permitting learning to take place in their home language throughout school. Therefore the aim of this paper is to analyse the progress and development of reading skills and knowledge of SA pupils from Grade 4 to Grade 5. Specifically, the variation in performance will be explored as to whether the contextual factors outlined above can be detected in the South African pupils' achievement profiles. Descriptive and inferential statistics will be applied to determine differences in achievement and correlations between home language, language of instruction and achievement. The latter is important in terms of determining the percentage of pupils actually attend school in the language of instruction that is the same as their home language and to explore to what extent does this disadvantage them in their learning.