This experimental study attempts to put to the test Cummins’ (1978) Linguistic Interdependence Hypothesis (LIH) in reading between English (L2) and Arabic (L3). Two groups of comparison and experimental attended this study. The experimental group received reading strategy instruction while the comparison group received the traditional form of reading instruction in L2. Both groups received reading comprehension tests in L2 and L3 before and after the instructions. An interview was finally conducted for a more in-depth investigation. Analysis of quantitative data evinced overall reading comprehension ability significantly improved only in the experimental group in both languages, supporting Cummins’ LIH. Componentially, only the inferential component improved significantly for the experimental group, showing different components contribute differently to the interdependence between languages. Qualitative findings showed miscellaneous results in linguistic, cognitive, and affective domains which were evidence of both interdependence and non-interdependence between L2 and L3. The pedagogical implication is further discussed.
