Widespread use and ubiquitous presence of smartphones have made mobile-assisted language learning (MALL) a valuable choice in language learning and teaching. Recent advancements in software development have transformed and revolutionized the realm of possibilities for language learning apps. With today’s great diversity in the MALL solutions available in the market, it is worthwhile to evaluate the effectiveness of different products to choose the most cost-effective options for learners’ best benefit. This study aimed to compare the effectiveness of three MALL procedures for vocabulary development in an upper-intermediate general English course at a university-affiliated language school in Kermanshah, Iran. To this end, three homogeneous classes, each with 11 learners, were organized after a general proficiency test and a test of vocabulary. The three MALL procedures used as classroom activity were playing Kahoot! mobile games, and using Memrise and Duolingo language learning mobile apps, during the final 30 minutes of each session. All other characteristics of the three classes other than the final-stage vocabulary development activity with the MALL procedures, were identical. Upon course completion, the learners took an extensive final test of vocabulary. The test results showed that learners in the class which used Memrise language learning app achieved the highest scores, followed by learners of the class in which Duolingo language learning app was used, and finally the class in which Kahoot! games were played. In all three classes, learners with better prior (pre-course) vocabulary knowledge and the more proficient learners demonstrated better performance in the final test. Further studies with higher numbers of learners of different levels and backgrounds, in diverse contexts and settings, and with different MALL procedures, apps and tools used for diverse language learning aims and objectives, are recommended.
