This study examined the mobile-assisted language learning studies published from 2007 to 2016 in selected journals from the aspects of adopted mobile devices, mobile learning systems/resources, and the benefits and challenges of utilizing mobile devices or learning systems/resources. The results revealed that the traditional mobile devices (e.g., Personal Digital Assistants, PDAs) and the current popular mobile devices (e.g., smartphones and tablet PCs) were frequently adopted for language learning in different time periods, while wearable devices have not been adopted by any language learning research so far. In addition, most of the studies used researcher-developed learning systems/resources, while the use of educational affordances of free applications or resources needs to be promoted. Furthermore, the abundant benefits of using mobile devices or mobile learning systems/resources for language acquisition were found in many studies, such as providing substantial chances for learning, and providing or building authentic environments for learners' meaningful knowledge construction; on the other hand, the studies also reported several challenges (e.g., insufficient practice time and the lack of effective learning strategies) to be overcome in the future. Finally, several suggestions are provided for researchers or practitioners to conduct their future work.