The purpose of this paper is to examine the current state of research on learner factors in second language acquisition by reviewing relevant studies published in English Teaching over the past 50 years. A total of 182 articles on various learner factors were extracted from the journal. Further detailed analyses were conducted on 110 articles on strategy, motivation, and personality traits in terms ofpublication year, research topics, participants, methods, and researchers' concentration. The results reveal that research on learner factors has significantly expanded over time in terms of volume and diversity, reflecting increasing research interests in the field. As for research methodology, a quantitative approach was far more frequent but qualitative and mixedmethod approaches have gained visibility since 2000. Yet, most of the studies focused on tertiary level learners, while overall neglecting primary and secondary level learners. Furthermore, individual researchers' interests in the factors looked rather sporadic as revealed in the lack of research concentration. Based on the findings, suggestions for future research on learner factors are made.