Technology-mediated learning has become a valuable tool, especially in the English language classroom. Nowadays, mobile learning is considered a significant educational tool for promoting education among learners. Several recent studies have attempted to examine different aspects of mobile learning. The size of the experimental group, and the duration and suitability of the assessment methods are important aspects in designing experimental studies in the context of mobile English language learning. Yet, very few studies have paid attention to these aspects. Therefore, this study aimed to investigate the utilisation of state-of-the-art mobile technology in English language learning, especially in terms of the size of the experimental groups, and the duration and suitability of the assessment methods. Following a systematic review protocol, 151 articles published between 2010 and 2017 were selected for analysis. Furthermore, this study considered, separately, three factors addressed in the reviewed studies: language acquisition problems, types of participants, and targeted English skills. The findings showed that the "group size" and "study duration" significantly differed among the studies based on the above factors. Questionnaires and tests were found to be the most common methods of "assessment" for each factor, whether used separately or in combination. The results of this review can assist in the formulation of experimental designs to mitigate the challenges and facilitate the effective use of mobile learning in English language learning.