Vocabulary learning is at the heart of language learning and language use. It is what makes the essence of a language. Having it in mind, most of the students always complain about lexical problems, and unfortunately, they are unaware of the different tools, which can help the students to learn vocabulary and improve vocabulary retention. A useful tool for learning and teaching vocabulary is a tool that uses authentic samples to enhance comprehension. Concordancing software is one of these digital tools that enable learners to explore billions of real-world materials. In this regard, the present study was conducted to investigate the actual effect of using this software on vocabulary retention. To gain this purpose, a sample of 54 intermediate female EFL students took part in this study. Participants were randomly assigned to two equal experimental and control groups. Before starting the treatment, the researcher gave the pretest to both groups. Then the treatment sessions were started for both groups, which lasted 12 sessions (4weeks); ten vocabularies were taught in each session and during this time the vocabulary of each lesson was taught by using concordancing software to the experimental group and by using a list of vocabulary to the control group. After the treatment sessions, the posttest was administered to both groups. The results of this comparison proved that the use of concordancing software improved learners' vocabulary knowledge. The outcomes have the potential to affect language learners' performance and teachers' beliefs about the effectiveness of using CALL programs, especially concordancing programs.
