Podcasting is being exploited incrementally by teachers as a tool for presenting educational content and encouraging language learning outside traditional classrooms. This paper reports on an investigation of three levels of podcast integration sustaining on the Iranian learner's lexical knowledge learning English as a Foreign Language (EFL). The learners were divided into three groups with high, low, and no integration of podcast into their syllabus. Data were collected from vocabulary pre- and post-tests administered to the sample: 90 intermediate students between 20 and 30 years old. The findings of the study indicated that there were statistically significant differences between groups with podcast integration and the one with no integration regarding their lexical knowledge in the way that the former outperformed the latter. The findings revealed that the improvement of the students in the high integration group is more than in the low integration group. On administering an attitude survey before and after the project, we found that they unanimously preferred podcasts as an interesting pedagogical tool. [For full proceedings, see ED564162.]