This study edition complements the parts of the String Quartets op. 20 that have already been published in Henle Urtext (HN 208); a new preface by Christin Heitmann provides illuminating background information. Haydn did not assign the nickname "Sun Quartets": it alludes to an edition of the time, in which the title page was decorated with a rising sun. The Quartets op. 20 are the last series in a group of earlier string quartets, but are clearly ahead of their time. The demanding fugues which close three of the six quartets are a particular structural feature.