Volume 20 contains works by Marx and Engels written between September 1864 and July 1868. It is the first in a group of volumes that reflect the theoretical and practical activity of Marx and Engels as leaders of the First International. The volume contains documents, reports, pamphlets, articles, statements and records of speeches which for the most part belong to the period of the foundation and further development of this first international mass proletarian organisation. A special section of the volume contains Marx’s notes and Engels’ reviews written in connection with the publication in 1867 of Volume One of Marx’s Capital. This section also includes a synopsis of Volume One made by Engels. The Appendices contain materials which throw light on the leading role of Marx on the Central (General) Council of the International and different aspects of his and Engels’ public activity.