This study examines the effect of communication strategy instruction on EFL students' oral communicative ability and their strategic competence. In a 14-week English as a Foreign Language (EFL) course (English Use II) based on Communicative Language Teaching approach, 80 learners were divided into two groups. The strategy training group (n = 44) received CS training based on a training program designed for the purpose of the present research, whereas the control group (n = 36) received only the normal communicative course using Click On 3, with no explicit focus on CSs. The communication strategies targeted in the training program included circumlocution (paraphrase), appeal for help, asking for repetition, clarification request, confirmation request, self-repair, and guessing. Pre- and post-test procedures were used to find out the effect of strategy training on language proficiency and CS use. The effect of the training was assessed by three types of data collection: the participants' pre- and post-IELTS speaking test scores, transcription data from the speaking IELTS test, and "Click On" Exit Test scores. The findings revealed that participants in the strategy training group significantly outperformed the control group in their IELTS speaking test scores. The results of the post-test transcription data also confirmed that the participants in the strategy training group used more CSs, which could be attributed to the CS training program. The findings of the present research have implications for language teachers, and syllabus designers.