Research on the effect of athlete leadership on pre-cursors of team performance such as team confidence is sparse. To explore the underlying mechanisms of how athlete leaders impact their team's confidence, an online survey was completed by 2,867 players and coaches from nine different team sports in Flanders (Belgium). We distinguished between two types of team confidence: collective efficacy, assessed by the CEQS subscales of Effort, Persistence, Preparation, and Unity; and team outcome confidence, measured by the Ability subscale. The results demonstrated that the perceived quality of athlete leaders was positively related to participants' team outcome confidence. The present findings are the first in sport settings to highlight the potential value of collective efficacy and team identification as underlying processes. Because high-quality leaders strengthen team members' identification with the team, the current study also provides initial evidence for the applicability of the identity based leadership approach in sport settings.Keywords: peer leaders, leadership, winning confidence, social identity approach, coaching, The most talented group of players does not always win a sports game. What matters is how well these players function as a team. In order to optimize this team functioning, effective leadership has been proposed as a crucial determinant (Cotterill, 2013). Although research in sport has typically focused on leadership of the coach (Chelladurai, 2007), recent research has established the importance of high-quality athlete leaders for the effective functioning of sports teams (Price & Weiss, 2011, 2013. In this regard, athletes are an important, but so far underinvestigated, source of leadership within sports teams.Building upon earlier work (Carron, Hausenblas, & Eys, 2005;Kogler Hill, 2001), Loughead and colleagues (2006) proposed a three-factor classification of athlete leadership functions: (1) task functions, which help the team to achieve its goal (e.g., giving teammates tactical advice); (2) social functions, which foster positive interactions between team members (e.g., caring for a good atmosphere off the field); and (3) external functions, which facilitate communication with people outside the team (e.g., with club management, media, and sponsors). Recently, empirical evidence has been reported for a fourth function, namely the motivational function (Fransen, Vanbeselaere, De Cuyper, Vande Broek, & Boen, 2014).The motivational leader is the best motivator on the field. This leader encourages his/her teammates to do their utmost, and initiates fresh heart into players who are discouraged.Although previous research on athlete leadership mainly focused on the team captain as the formal leader of the team, recent empirical evidence demonstrated that informal leaders rather than the captain take the lead, both on and off the field . We will therefore focus on the leadership quality of the best athlete leader on each of the four leadership roles instead of investigating the leadershi...