This study examines endorsement and authorization as two social mechanisms that can induce perceptions of legitimacy for individuals who manage work teams. "Endorsement" is the support of a manager by one's own team members, whereas "authorization" is the support of a team manager stemming from a higher bureaucratic level. Applying these mechanisms to specific work teams we hypothesize that (1. a team member who observes that other team members endorse a manager and the upper management authorizes the manager will perceive that manager's acts to be more legitimate; (2. in the context of the team environment the effect of endorsement will be greater than that of authorization; and (3. perceived legitimacy will mediate the effects of endorsement and authorization on positive outcomes such as team members' efficacy and commitment. These hypotheses were tested using 320 respondents from 56 Korean work teams. The results provide overall support of these hypotheses. As predicted, endorsement and authorization are key mechanisms significantly enhancing legitimacy. Further, the effect of endorsement on legitimacy is greater than that of authorization, and legitimacy partially mediates the effects of both endorsement and authorization on team efficacy and commitment. The implications of these findings are discussed in the context of prevailing theories of legitimacy.