This research attempts to investigate the degree of students’ achievement in reading comprehension in English as a foreign language through explicit instruction in metadiscourse markers. For this purpose, 80 students studying at a language school (placed at intermediate levels of English language proficiency) were chosen to participate in the experiment. Every possible measure was taken to ensure that the participants lacked enough knowledge about metadiscourse. The participants were then randomly divided into four equal groups each containing twenty students. The first experimental group (EG1) included twenty participants who received instructions in both textual and interpersonal metadiscourse. The second experimental group (EG2) received instructions in only textual metadiscourse markers. The third experimental group (EG3) received instructions in only interpersonal metadiscourse. The control group received no specific instructions in metadiscourse and was only exposed to some input enhancement material and relevant exercises.

As a result of running a number of statistical procedures, instruction on metadiscourse revealed a positive effect on the participants’ achievement in reading comprehension in English. The results of the study have some implications for materials designers; they can improve a learner’s ability to understand and remember information from the text by improving it textually and interpersonally.