The present study sought to investigate the effect of explicit instruction of lexical bundles (LBs) on the development of Iranian English for Academic Purposes (EAP) students’ writing quality and also their receptive and productive knowledge of Lexical Bundles (LB). Assigned to two experimental and control groups, the eighty participants took pre- and post-tests of writing tasks and the receptive knowledge test. Afterwards, the obtained scores were subjected to a series of Analyses of Covariance (ANCOVAs) and paired samples t-tests. Results of the within-group and between-group analyses indicated that explicit instruction of LBs enhanced the participants’ productive and receptive knowledge of LBs and also improved the overall quality of their written productions. Possible explanations are provided and the implications of the findings for the applicability of LBs instruction are discussed.
