This study investigates external and internal factors affecting students’interaction in English-speaking classes to develop effective strategies to improve theirinteraction. The study was conducted among sixteen classes at the Faculty of English at HanoiOpen University, with 86 students in total. Questionnaires and interviews were employed asdata collection instruments for the study. The results showed that there are still a large numberof ‘passive’ students who are not willing to speak and participate in class activities for differentreasons, both coming from external and internal ones. These factors mainly include “selfconfidence”, “motivation, and interest”, “prior relationships”, “classroom environment,”“lecturers’ teaching styles”, and “technological devices”. Accordingly, different techniques andteaching methods were recommended to promote students’ interaction during speaking lessons,including “pair work,” “asking-answering questions,” “debate sessions or discussion,” and“interactive multimedia learning.” The study results are expected to help both students andlecturers identify influential factors and explore more effective strategies or teaching methodsto enhance students’ participation in English-speaking classes.