Persons in the shadows may substantially affect how an individual acquires expertise, through, for example, guiding deliberate practice. In the domain of popular music, such persons in the shadows might be peers, parents and teachers. Little research exists on how individuals perceive the impact of persons in the shadows on expertise development, particularly in fields like popular music. This study investigates the perceived impact exerted by peers, parents and teachers on the expertise development of guitarists in the domain of popular music. Interviews were used to investigate nine case studies of guitarists with different expertise levels (experts, sub-experts, amateurs). The main focus was on the roles of persons in the shadows concern...