This research examines authentic leadership emerged recently as one of the most interestingleadership research topics. Authentic leadership has emerged as an umbrella concept over thelast several years bridging the leadership, spirituality, and positive organizational behaviorliteratures. In this study, I define authentic leadership as a leadership with greater self-awarenessand self-regulated behaviors on the part of leaders and associates, fostering positive selfdevelopment(Luthans and Avolio, 2003). Among others, two key constructs of authentic leadershipare self awareness and self regulation. Self-awareness refers to the extent to which leaders understand their strength, motives, andmission. Self-regulation is the process through which leaders strive to maintain and pursuetheir mission and goals in light of their values. Researchers insist that authentic leaders cancontribute to hard performance as well as soft performance such as organizational commitment,job satisfaction, and OCB. In this study, I hypothesize the effects of transformational and authentic leadership on teamperformance and examine team energy as positive emotion and team efficacy as positive cognitionas mediation mechanisms between leadership and team performance. These mediation mechanismsdovetail with the research of positive psychology shifting the focus in psychology from dysfunctionalmental illness or negativity to mental health or positivity. This hypothesis calls attention toorganizational members' happiness, strength, or wellbeing. To advance the team-level analysis, I collected data from 693 employees from 121 teams, 4industries. The sample consisted of 583 males and 110 females. The mean of team tenure of participants was 3.8 years and the mean number of team size was 5.72. I designed a robustresearch model in order to assess model fit and avoid issues of common method variance. Usingthe verified model, standardized path coefficients were examined to test research hypotheses. Supporting the most predictions, the results show that authentic leadership has a positiveimpact on team performance and this relationship was partially mediated through team energyand team efficacy. However, the effects of transformational leadership on performance andteam efficacy disappear after the effect of authentic leadership controlled for; the relationshipbetween transformational leadership and team performance is fully mediated by team energy. This findings suggest that previously known effects of transformational leadership on teameffectiveness be overstated. Even though transformational leadership still has an effect on team performance through teamenergy, this research suggests that various styles of leadership such as charismatic, transformational,or visionary leadership 'without authenticity' could be a liability, because they could be perceivedas mere skills and gestures by the followers. We discuss implications of findings in details.