The bottom line is that Bartók did not write a viola concerto. Towards the end of his life, the British violist, William Primrose commissioned him to write a concerto, but Bartók was unable to finish it. He channelled his remaining energy into completing the Third Piano Concerto instead.
Only 14 pages of manuscript material remain of sketches for the concerto. One of these is an early, rejected sketch for the first movement. In the remainder, the material of the first movement can be clearly followed, and what is missing can be filled in on the basis of analogy and common sense. There are even notes on orchestration. In the case of the other movements, the situation is profoundly obscure. There survives a conspicuously short slow section, there is a type of introduction for viola solo, leading to some kind of music in C major and 2/4 time (in the final bar, Bartók indicates that 2/4 is to follow). There are also some sketches for a dance-like finale – another page remains, full of obscure jottings. After Bartók’s death, Tibor Serly undertook to save what he could. He felt it was best to create a traditional three movement work, with a slow movement in the middle. Although he was extremely careful in his work, there is no arguing that the composition he finally produced did not reflect Bartók’s original intentions. For example, it now seems highly likely that the “introductory” viola solo was never intended to be placed before the slow section. And yet this peculiar semi-work has been quite a success since its premiere. In spite of its less convincing sections, here and there, true Bartók is instantly recognisable. It is in what Bence Szabolcsi called the “warmly melodic” style that blossomed during his American years, and which began with the Violin Concerto. The music, which in a sense has been brought back from the dead, is uniquely interesting and mystical.