In this article we examine the reading ability of Grade 4 learners in their home language, isiZulu and in English (first additional language), using both eye-tracking activities and traditional pen-and-paper reading comprehension assessment. The aim of the study was twofold: firstly, to compare bilingual reading performance in an agglutinating language (isiZulu) and an analytic language (English). The learners’ eye-tracking profiles were obtained in both languages to see how they differed across the two languages and their eye-tracking profiles were also analysed according to their comprehension performance in both languages. Secondly, the eye-tracking profiles in both languages were also analysed in terms of reading ability, to determine how eye-tracking profiles differed among strong, average and weak readers in the two languages. In general, pen-and-paper tests showed that the entire group read with relatively low comprehension. The main findings from the eye tracker showed significant differences when the learners read in the two languages, on nearly all the selected eye-tracking variables. The eye movement profiles in isiZulu may be attributable to the longer word units in the conjunctive orthography of isiZulu. However, although there were several significant differences in eye movements between the reading ability groups in English, differences in eye movements due to differential reading skill did not emerge strongly in isiZulu. This may be due to floor effects in novice isiZulu readers or to a longer developmental trajectory in the early stages of reading in isiZulu. Some implications for early reading instruction in isiZulu are briefly considered.