Background: Persian English learners committed mistakes and errors which were due to insufficient knowledge of different senses of the words and collocational structures they formed. Purpose: The study reported here was conducted for a thesis submitted in partial fulfillment of the requirements for The Master of Arts degree, School of Graduate Studies, Islamic Azad University, Khorasgan Branch, Esfahan, Iran. Setting: The Iran Language Institute, Kerman, Iran. Study Sample: Sixty low-intermediate male EFL students, aged 17-25, at Iran Language Institute in Kerman, were screened out from among 286 level 5 students through administering the Oxford Placement Test. Intervention: The materials used in this study consisted of instructional materials and measurement tools as follows: 2.2.1. Instructional Materials. The instructional materials were 150 collocations and words chosen from A Course in English: Books 3, 4, and 5 used at Iran Language Institute (ILI). More than 50% collocational and sense related lexical items were selected and designed to be explicitly taught to the experimental group (EG) and were implicitly taught to the control group (CG) by the researcher himself throughout an eleven-week long-term with two one-hundred and twenty-minute sessions each week for both groups. Research Design: Experimental; Control or Comparison Condition: The selected subjects were randomly assigned to the groups: experimental and control. Data Collection and Analysis: A t-test was run to make sure that the two groups were homogeneous at the entry point. Another t-test was run to find out the differences between the means of the two groups at the end of the program. A factorial analysis of variance was run to determine the probable significant differences in the performance of the subjects on EAT and its different modules. Findings: t-value results demonstrated that both groups were homogeneous at the initial point after the administration of the Oxford Placement Test (t(56)= 0.14, p=0.89). Whereas the second t-test after EST revealed that the difference between the means of the two groups was highly significant and the experimental group outperformed the control group (t(57)= 5.29, p=0.000) (see Table 1 below). Conclusion: The weaknesses and limitations of this study notwithstanding, it offers a new insight and sheds more light on the nature of collocations and different senses of a word, both for practical and theoretical purposes. Citation: This project was an attempt to stipulate the collocational and sense-related aspect of lexical items in low-intermediate language learners due to practical limitations and which the researcher thought to be the suitable level. Further research is required to demonstrate: a) Whether vocabulary misplacement and collocational clash will be a main source of errors in high-intermediate and advanced learners. b) Which aspect, collocational clash or sense, will be the main source of errors in L2 learners? c) Whether collocation and sense teaching makes any difference in language learners and what a better course content can be in this relation? d) Which other aspects of lexical items, such as idioms and metaphors, replicate the same results? e) What will the role of translation-equivalents be on higher levels of language comprehension and production such as paragraphs and passages? To sum up, the researcher hopes that this study has provided some motivations for further investigations by envisaging some interesting and provoking research questions in the field of second language acquisition, particularly interlanguage development. (Contains 3 tables.)