As the political left continued to fragment, at the end of 1919 Gertrud and Eduard Alexander became founder members of the Communist Party of Germany.
[1] During her time as editor of the "Feuilleton" supplement between 1919 and 1925 around 160 of her contributions appeared, and she was widely seen as the most important arts and culture critic in the Communist Party.
[1] In the so-called Kunstlump debate, ignited on the political left during 1920, Alexander took a position resolutely opposed to that of John Heartfield and George Grosz.
[1][7] With her husband and elder son she participated in the Marxist Work Week (conference) in May 1923 which prepared the way for the creation of the Frankfurt based Institute for Social Research.
[1] In 1925 she relocated to Moscow (accompanied by her two young sons) from where, till 1930, she worked as a correspondent for the Die Rote Fahne ("The Red Flag").
Between 1931 and 1939 she held a position of responsibility with the "Main Administration for Literary and Publishing Affairs" ("Glavlit" / "Главное управление по делам литературы и издательств" / "Главлит") (which was concerned with censorship).