The study examined profiles of reading skills and cognitive skills for South African children from schools that differed
in opacity of medium of instruction. The sample included 122 third graders instructed in Afrikaans (transparent
language), 109 in Setswana (transparent), and 127 in English (opaque). The link between cognitive skills
(short-term memory and working memory) and reading comprehension was expected to be mediated by phonological
awareness, word fluency, text fluency, and vocabulary. Multigroup invariance analyses revealed differences
in strength of relations between cognitive skills and reading skills across mediums of instruction. For
English, phonological awareness played a smaller and vocabulary a larger role compared to Afrikaans and
Setswana, largely in line with theories on orthographic depth and reading; furthermore, predictors of reading
comprehension showed weaker interrelations in Afrikaans and Setswana. Our study stresses the need to align
reading instruction with orthography