Written: Written in July—August 1915. Published: Published in pamphlet form in the autumn of 1915 by the Sotsial-Demokrat Editorial Board in Geneva. Published according to the pamphlet text. Source: Lenin Collected Works, Foreign Languages Press, 1970, Peking, Volume 21, pages 295-338. Proofed and Corrected: Alvaro Miranda and Andy Blunden, 2022. Transcription\Markup: E. O'Callaghan Public Domain: Lenin Internet Archive (2005). You may freely copy, distribute, display and perform this work; as well as make derivative and commercial works. Please credit “Marxists Internet Archive” as your source.
[*][Note: All early editions of Socialism and War in several languages, including those published while Lenin was still alive, clearly acknowledged Zinoviev as co-author of the document. The Soviet English language edition of the Lenin Collected Works acknowledges Zinoviev’s involvement (see footnote  below), but, without explanation, omits him as co-author.—Ed.].
Lenin decided to write the pamphlet Socialism and War (The Attitude of the R.S.D.L.P. Towards the War) in connection with the preparations for the First International Socialist Conference. G. Y. Zinoviev helped write the pamphlet, though most of it was drawn up by Lenin, who, moreover, edited the entire text.
The pamphlet was published in German in September 1915 and distributed among the delegates to the Zimmerwald Socialist Conference. In 1916 it was published in French.