During the second half of the 20th century, Bo Wallner (1923-2004) was an influential person in Swedish musical life; highly regarded by those who shared his opinions, and harshly criticised by those with other aesthetic ideals. As a pedagogue, musicologist, author, broadcaster, and mentor for composers and musicians, as well as a sharp ideologue, he broke new ground. The purpose of the project is to write a contextualised scholarly biography of Wallner's wide-ranging activities. All his life he was whole-heartedly committed to supporting contemporary music. He was very close to many composers, and for some of them he acted as a spokesman. One of the aims will be to analyse Wallner's social network, which made it possible for his ideas to receive a sympathetic hearing, whilst another aim is to describe his ideology. Wallner's writing is truly extensive, while as a musicologist his most important achievement was his biography of the Swedish composer Wilhelm Stenhammar (1874-1927). Yet what was his relationship to research? Wallner endeavoured to bridge the gap between musicology and musical performance. For instance, at the Royal College of Music in Stockholm, where he taught history of music and form study for more than 40 years, he often used form analysis to help with musical interpretation, and he was a pioneer in this field. When writing the history of music in Sweden after the Second World War, it is thus necessary to determine Wallner's role. There are numerous opinions as to this, but what is the truth and what is myth?