The contribution of computer-assisted instructional programs to language learning process has been the focus of researchers for about two decades. However, the effect of synchronous and asynchronous computer-assisted approaches of language teaching on improving L2 vocabulary has been scarcely investigated. This study explored whether synchronous, asynchronous, and integrated approaches had any significant impact on vocabulary achievement of Iranian EFL learners in an intensive reading program. The participants were 120 students, majoring in English Teaching and Translation Studies at Islamic Azad University of Abadan. The participants were at intermediate level of language proficiency. They took a vocabulary pretest and posttest before and after the treatment. The results showed that there was a significant difference between the traditional approach and the other three approaches. That is, computer-assisted teaching approaches significantly influenced EFL learners’ vocabulary learning. The findings also manifested that integrated approach exerted significant influence on improving L2 vocabulary achievement of language learners. The findings implied that language learners, who were thought under computer-assisted approaches, had more autonomy and self-efficacy and showed more intrinsic motivation to learn the target language than the learners who were taught under traditional approach. Thus, computer-assisted approaches can help language teachers create more fruitful learning atmosphere to reduce distressful factors and accelerate learning process.