Convictions are strong that multimedia courseware holds great promise for enhancing learning efficiency among learners. This study thus aimed at comparing the effects of the multimedia programs introducing 100 vocabulary items through pictures and streaming video with those of teacher instruction on increasing EFL learners’ vocabulary repertoire. A total of 120 subjects were identified as intermediate-level students based on the scores they obtained on the reading and listening sections of an IELTS and were randomly assigned to four equivalent groups. One group served as the pilot group, two as the experimental groups, and the other as the control group. The pilot group participated in the pilot study of the vocabulary test that was designed by the researcher as the pre- and posttest. The two experimental groups received treatment on teaching the vocabulary items through a Motion-Picture Multimedia Program (MPMP) or a Still-Picture Multimedia Program (SPMP). The control group received a treatment on the same vocabulary items through teacher instruction. The results favored the use of the multimedia programs, albeit the multimedia program drawing on streaming video proved to be more effective than the one using still pictures. Therefore, the findings revealed that dual coding of vocabulary might occur at different degrees across different methods of vocabulary teaching, resulting in varying degrees of the learning success.