She took an active interest in politics from an early age and found out firsthand about the consequences sometimes bestowed on those holding minority views on such matters when she was fired from her job in 1896 for wearing a button supporting populist Democrat William Jennings Bryan.

[3] Her experiences in this capacity were the inspiration for her muckraking magazine series, "Letters of a Pork Packer's Stenographer," which exposed the dangerous working conditions and inadequate wages which prevailed throughout the packing industry.

"[5] Marcy emerged again as a sharp critic of the tactics of her employer, emphasizing the need of the poor for concrete physical assistance rather than paternalistic lectures about morality and the winnowing of "worthy" from "unworthy" recipients of aid.

[8] Moving from its origins as a dry theoretical magazine edited by A.M. Simons in its earliest years, by the end of the first decade of the 20th Century Kerr and Marcy had made the Review into an illustrated slick-paper publication which provided an aggressive voice to the left wing of the socialist movement.

[9] During 1910 and 1911 Marcy published a series of eight articles in International Socialist Review called "Beginners' Course in Socialism and the Economics of Karl Marx," which attempted a popularization of the main ideas of Marxism.

With the American declaration of war against Germany on April 7, 1917, the anti-militarist International Socialist Review became subject to an intensifying series of repressive government actions, including United States Post Office Department surveillance,[13] and denial from the mails.

[14] Cut off from its ability to reach its subscribers, the publication was terminated early in 1918, the same year in which Marcy joined the revolutionary union the Industrial Workers of the World (IWW).

"[19] Marcy's argument went unheeded and the Socialist Party split asunder along factional lines, ending in the formation of two new communist organizations in addition to the regular SPA and beginning a catastrophic spiral of decline.

[20] Demoralized by the disintegration of the American left in the years after the conclusion of World War I and suffering depression exacerbated by the loss of her Bowmanville, Illinois, home, Mary Marcy died by suicide from poison on December 8, 1922.

"[22] Her book, Shop Talks on Economics, is regarded as a classic of socialist propaganda literature and was translated in its day into Japanese, Chinese, Ukrainian, Romanian, Finnish, French, Italian, and Greek.