Post-Apartheid South Africa has undergone an educational language policy shift from only Afrikaans and English in education to the representation of all 11 official languages: Afrikaans, English, isiZulu, isiXhosa, isiNdebele, siSwati, Sesotho, Setswana, Tshivenda and Xitsonga. The national languages policy included the Language in Education Policy (LiEP), which stipulates that learners from grades 1- 3 in all ways possible should be provided the opportunity to be taught in their home language (HL). With this change, there has been a need to increase access to African languages in education. The 2007 Status of LoLT report released by the Department of Education (DoE) revealed that since 1996 up to 65% of learners in the foundation phase are being taught in their home language. In other ways, the LiEP has been successful in bridging the gap of access to African languages in the basic education system. With that said, there has been rapid growth of interest in early childhood crosscultural literacy assessment across the globe. Internationally South Africa has participated in the Southern and Eastern Africa Consortium for Monitoring Education Quality as well as the Progress in International Reading Literacy Study studies. The design of these particular international studies meant participation in the same assessment but in different languages, calling into question the equivalence of assessments across languages. Assessing across languages should aim to encourage linguistic equivalence, functioning equivalence, cultural equivalence as well as metric equivalence. South Africa has taken part in three cycles of the Progress in International Reading Literacy (PIRLS) study. The purposes of the current study is to present secondary analysis of the prePIRLS 2011 data, to investigate any differential item functioning (DIF) of the achievement scores between English and isiXhosa. The Organisation for Economic Co-operation and Development (OECD) developed a framework of input, process and output for curriculum process. The framework shows the multiple facets that needs to be considered when implementing a curriculum in a country. The curriculum process framework was used as the theoretical framework for this study. The framework views curriculum success as a process of measuring how the intended curriculum (input) was implemented (process) and should be reflected in the attained curriculum (output). The adapted framework is LiEP as the attained curriculum, as learners in the prePIRLS 2011 are tested in the LoLT in Grades 1-3. Followed by the prePIRLS 2011 assessment, as the implemented curriculum testing the learners’ comprehension skills requires by grade 4 in their HL. Lastly, the attained curriculum refers the learners’ achievement scores in the prePIRLS 2011 study. A sample of 819 Grade 4 learners (539 English L1 speaking learners and 279 isiXhosa L1 speakign learners) that participated in the prePIRLS 2011 study were included in this study. These learners wrote a literary passage called The Lonely Giraffe, accompanied by 15 items. The study made use of the Rasch model to investigate any evidence of Differential Item Functioning (DIF) on the reading achievement of the learners. The findings showed that the items did not reflect an equal distribution. In addition, an item by item DIF analysis revealed discrimination on one subgroup over the other. A further investigation showed that these discriminations could be explained by means of inaccurate linguistic equivalence. The linguistic equivalence could be explained by means of mistranslation and/or dialectal differences. Subsequently, the complexities of dialects in African languages are presented by providing isiXhosa alternative translations to the items. The significance of the current study is in its potential contribution in further understanding language complexities in large-scale assessments. Additionally, in attempts to provide valid, reliable and fair assessment data across sub-groups.