This study aimed to investigate the impact of self-regulation training and instruction on EFL learners’ short-term andlong-term retention of English vocabulary in online classes. The design of the present study was a quasi-experimental pre-test post-test control group design. The participants of this study included 60 Iranian maleintermediate EFL learners chosen from among 68 learners studying English at a private language institute inKerman, Iran based on their PET scores. The original sample was selected through convenience sampling. Theparticipants’ ages ranged from 17 to 30. The following instruments were used in this study: a Preliminary EnglishTest (PET) and two researcher-made vocabulary tests. To analyze the data, the Kolmogorov-Smirnov test,Descriptive statistics and Repeated Measures ANOVA were used and according to the results of data analysis, self-regulation training and instruction had a significant effect on EFL learners’ short-term and long-term retention ofEnglish vocabularies in online classes. The findings have some implications for EFL teachers, EFL learners, andcurriculum planners. Manuscript profile