Research examining athlete leadership within sport has identified the presence of informal leaders (Loughead, Hardy & Eys, 2006), which benefit both team functioning and team cohesion (Price & Weiss, 2013; Carron, Colman, Wheeler & Stevens, 2002). Although there is limited attention to the concept of informal leadership, research focusing on informal roles have identified both positive and negative functions (Cope, Eys, Beauchamp, Schinke & Bosselut, 2011). Literature has highlighted a link between informal leaders and positive team functioning (Price & Weiss, 2013). This study aims to explore this, by exploring the consequences, characteristics, behaviours, causes for behaviours and development strategies surrounding the identified informal leaders. The study adopts grounded theory (Weed, 2009), while collecting data via a semi structured interview process, involving 8 participants. Braun and Clarke’s (2006) thematic analysis approach, was employed for data analysis. The findings established both positive and negative consequences of informal leaders, whilst behaviours and characteristics were identified. Causes for behaviour highlighted personality, leadership and team related factors contributing to their actions. Informal leader strategies were both recommended and found to be effective, which contributed to their leadership quality. The importance of understanding informal leadership within the athlete leader concept is therefore warranted and encouraged in future research.