The present study attempts to investigate the effect of integration of conscious and unconscious learning processes on improving EFL students’ vocabulary acquisition. To do so, 50 male language learners studying English as a foreign language (EFL) at two language institutes in Arak were selected. To determine the participants' level of language proficiency, the Oxford Placement Test (OPT) – 2nd version – was administered. Based on the OPT test results, 40 homogenized learners were chosen out of a population of 50. Next, the students were randomly put into three groups: Group A (conscious learning process), Group B (unconscious learning process), and Group C (integration of conscious and unconscious learning processes). A course was designed to help students improve their vocabulary. For that, the instructor selected 180 words from a total of 504 Absolutely Essential words book. Then, to check the level of the words, an internet engine called English Vocabulary Profile was employed. A total of 90 words were chosen at the same level as the participants. The vocabulary test was given to the participants of all groups before the first session as a pre-test. During the study, group A was taught vocabulary through conscious learning process, group B through unconscious learning process, and group C through the integration of conscious and unconscious learning process. After 10 sessions of treatment, a post-test with the same questions as in the pre-test was given to the participants. The participants’ scores were compared using mean, standard deviation, Mixed ANOVA, and Paired Samples T-test. The results indicated the superiority of the learners’ performance in the integrated learning process group over the other two groups. It also showed that English learners in the conscious learning process group had a better performance than the ones in the unconscious learning process group. In general, the findings of this study showed that, although both conscious and unconscious
