The collection consists primarily of personal and editorial correspondence, and also includes documents and circulars from the Association Internationale de Travailleurs (International Workingmen's Association). The correspondence mainly concerns the international anarchist movement and the anarchist, anti-Fascist role in the Spanish Civil War. Mrachnyi was known to most of the correspondents under the pseudonyms Mraschnyi or Mratchny, but he also used his original name, Klavansky, in Europe and Clevens in the United States. His wife used the name Johanna Clevens, reverting to her maiden name, Boetz, after their divorce.
The papers are in English, French, German, Russian,Spanish, and Yiddish. Translations of most of the Russian items were provided by Charles Gilbert. Articles received for publication in Fraye Arbeter Shtime (Freie Arbeiter Stimme) have been removed to the FAS collection.
According to his oral history in Paul Avrich's Anarchist Voices (Princeton University Press, 1995), Mark Mrachnyi was born Mark Klavansky in Kovno, Lithuania in 1892. During the Russian Revolution of 1917, Mrachnyi became involved in the anarchist movement. It was then that he adopted the pseudonym Mrachnyi, from the Russian word for "gloomy." Between 1917 and 1920, he edited a series of anarchist journals, including Nabat and Nestor Makhno's Put'k Svobode. In 1920, Mrachnyi, along with many other anarchists, was imprisoned by the Bolshevik authorities. He remained in prison until he was deported in 1922. He then settled in Berlin, where he remained active in anarchist politics and also studied psychoanalysis. In 1927, he moved to Canada. After several years in Canada, he moved to the United States.
In 1934, he assumed the editorship of Fraye Arbeter Shtime (Freie Arbeiter Stimme), the foremost Jewish anarchist journal in the United States. During Mrachnyi's tenure, the journal energetically covered events in Spain. The failure of the anarchist efforts in Spain came as a crushing blow to him. In 1940, a disheartened Mrachnyi resigned his editorship, and abandoned his anarchist activism. From that time until his death in 1975, Mrachnyi practiced psychoanalysis in New York City under the name Mark Clevens.
