The present study set out to identify grammar, vocabulary and reading strategies most and least frequently used by Iranian ESP students. One hundred and eighty two male and female undergraduate Iranian ESP students studying at Bu-Ali Sina University, Kurdistan University, and Malayer University took part in the study by completing Grammar Learning Strategy Questionnaire developed by Gutara (2008), Vocabulary Learning Strategies Questionnaire developed by Soodmand Afshar, Ketabi, and Tavakoli (2012), and Survey of Reading Strategies developed by Mokharti and Sheorey (2002). Regarding grammar learning strategies, the results of descriptive analyses indicated that taking notes, seeking teacher’s explanation and using L1 for comparison were most frequently used, whereas writing emails and compositions, using new structures in speaking and writing, and learning in group were least frequently used. Concerning vocabulary learning strategies, it was found that memorizing, repeating orally and using bilingual dictionary were among the most frequently-used strategies, whereas using loci method, listening to live TV programs, making sentences, and drawing pictures were employed least frequently. Finally with regard to reading strategies, paying closer attention when text becomes difficult, reading slowly and carefully when text becomes difficult, re-reading to increase understanding were found to be utilized most frequently, while paraphrasing, analyzing critically, taking notes, and using typographical features were used least frequently. The possible reasons why the results turn out to be so as well as the implications of the study are discussed in detail in the paper.
