According to Oxford (1990), different learner variables affect the choice of learning strategy. It was also found that effective L2 readers know how to use strategies to foster reading comprehension and ineffective readers have little awareness of strategies to read effectively (Yang, 2002). This study investigates the contribution of three relatively important variables and their components (namely, the cognitive domain or awareness and use of strategies, the linguistic domain or general English proficiency level, and the affective domain or attitude toward reading in L2), to reading strategy use in English. The second purpose of the study is to find out the effect of reading strategy use on reading comprehension. For these purposes, 100 undergraduate Iranian EFL students participated in this study. They were given Language Proficiency Test, Test of reading comprehension in English, Reading Strategy Awareness and Use Questionnaire, and finallvy a questionnaire on attitude toward Reading. The obtained data were analysed using descriptive statistic (means, standard deviations), Pearson correlation procedure, regression analysis, ANOVA, and Scheffe post-hoc multiple range test. Analysis of data showed the three aforementioned variables, namely awareness and use of reading strategies, linguistic proficiency, and attitude toward reading had significant contributions to strategy use. However, strategy awareness showed to have the most contribution to strategy use. In addition, among the subgroups of strategy awareness, the metacognitive component showed to contribute more to strategy use. In this study it was also found students with higher strategy use gain better scores on the reading test. It is concluded that as degree of strategy use affects reading performance, in order to improve effective use of reading strategies teachers and learners should pay more attention to the development of awareness of reading strategies, especially the metacognitive component in order
