This study examined the TEDster’s use of communicative features of stance and engagement in the corpus of a total of 500 TED talks in five different disciplines, 100 talks per discipline. In so doing, the stance markers in three levels of certainty and the engagement markers of interpersonality were identified, and the occurrence frequencies of the markers were statistically analyzed. The main findings are as follows: First, TEDsters were overall moderate in conveying certainty. Second they revealed their own individual self-identity more frequently than their collective selves-identity. Third, those in certain disciplines (e.g. art and design) used I to explicitly comment on their own achievements while another disciplines (e.g. politics and global issues) used we to implicitly reveal both their own identity and the audience. The findings showed the possibility of disciplinary-specific classification of metadicourse in TED talks as a popularized spoken genre.