The most important project of Haydn research in the 20th century, the first complete critical edition Joseph Haydn Werke will be completed in 2014. It is compiled by the Joseph Haydn Institute at Cologne, which was founded in 1955 and stores a comprehensive collection of sources, reproductions and all the Haydn literature. Beyond the complete edition basic philological work remains to be done — and should be done at this research center: A new edition of Haydn’s letters and a new catalogue raisonné replacing the outdated one by Hoboken.