Following a murder attempt by Herman Helcher, a mentally ill former student of hers, her physical health rapidly deteriorated and she never fully recovered, but was able to return to writing and public speaking after a few years.

Her biographers, Paul Avrich and Margaret Marsh, and collectors of her writings, such as A. J. Brigati, Sharon Presley and Crispin Sartwell, brought her life and work back to public attention by the turn of the 21st century.

[12] She and her sister spent much of their time at home reading poetry and novels by British writers, with Lord Byron in particular becoming a strong influence on De Claire's writing style.

[40] Again struggling with poverty, she offered her services as a private tutor for handwriting, music and the French language;[41] in late 1885, she moved in with her aunt in Greenville, Michigan, to pursue this line of work.

[51] As the years went by, de Cleyre became increasingly famous among freethinking circles, motivating her to undertake lecture tours for the American Secular Union,[52] which took her throughout the Midwestern and Northeastern United States.

[53] She would always return to Michigan, where she would stay at her place in Grand Rapids, her aunt's house in Greenville, or visit her family in St. Johns; her sister and mother disapproved of her new-found radical politics and talked very little about their opinions.

[54] Demand for de Cleyre as a speaker and writer grew throughout the United States, as she contributed prose and poetry to several freethought periodicals, including The Truth Seeker.

[85] On June 12, 1890, de Cleyre gave birth to their son Harry,[86] but her chronic condition and depressive mood made her feel physically and emotionally incapable of raising him.

[96] In her later essay, "The Making of an Anarchist", she praised the Jewish community's dedication to their education and commitment to the radical movement, even in the face of extreme poverty and antisemitism in the United States.

[99] She regularly read and contributed articles to the Yiddish anarchist magazine, the Fraye Arbeter Shtime, warning the editor Saul Yanovsky against cutting up or changing her words when translating them from English.

[123] Through the LLL, she met Margaret Perle McLeod and Natasha Noshkin,[125] with whom she helped establish a Radical Library that provided an education space for Jewish anarchists in Philadelphia.

[131] As her health declined due to overwork and arguments with her partner Gordon increased, her fellow magazine contributors Harry Kelly and John Turner convinced her to visit the United Kingdom.

[157] She began writing regular reports on the United States for the Freedom newspaper in London, and started a translation of Jean Grave's Moribund Society and Anarchy.

[162] She was able to find a quiet farm in Torresdale, owned by the spiritualist Sada Bailey Fowler, where being closer to nature provided a peaceful and relaxing environment for her to recover in.

[172] The group's propaganda activities began to face difficulties in the wake of the assassination of William McKinley by Leon Czolgosz, which unleashed a wave of political repression against the anarchist movement.

[175] In March 1902, after Senator Joseph R. Hawley offered $1,000 (equivalent to $35,215 in 2023) to take a shot at an anarchist, de Cleyre publicly accepted his challenge in an open letter published in the Free Society newspaper.

[178] Although de Cleyre had previously rejected violence as a pacifist, her sympathy for Czolgosz's attack against McKinley marked a turning point, as she increasingly began to accept violent methods such as propaganda of the deed.

[184] On December 19, 1902, de Cleyre was shot three times at point blank range by Herman Helcher,[185] a former student who had developed an obsession with her and harbored paranoid delusions about her actions.

[203] As her trip coincided with German kaiser Wilhelm II's state visit to Norway, the local press speculated whether she was intending to assassinate him and she was closely surveilled by the Norwegian police from the moment she arrived.

[207] Upon her return to the United States, her health suddenly experienced a dramatic decline; her chronic condition was finally diagnosed as an atrophy of tissues caused by a catarrh in her nose.

[243] While continuing to teach in the evenings, de Cleyre dedicated herself to anarchist activism, overseeing the integration of the Social Science Club and Radical Library into The Workers Circle.

She was ultimately dissatisfied with the $250 (equivalent to $7,893 in 2023) which she managed to collect for the revolution,[282] expressing frustration that American libertarians had been so slow and ineffectual in aiding the struggling Mexican revolutionaries.

[286] Together with Berkman and Goldman, she publicly defended the bombing suspects, the McNamaras, and accused the labor leaders Samuel Gompers and Morris Hillquit of hypocrisy for demanding they be punished.

She asked why they had not demanded justice for the many more workers who had died in the Johnstown Flood of 1889, Panic of 1907 and Cherry Mine disaster of 1909, and declared that such events had made violence against the capitalist system a necessity.

[287] During the San Diego free speech fight of 1912, she expressed outrage that one hundred members of the IWW "had been made to kneel and kiss the flag", declaring that she would rather have been shot than forced to prostrate herself.

[304] De Cleyre rejected the idea that gender roles were natural, pointing out that they were products of socialization, where girls were prohibited from exhibiting masculine behavior and vice versa.

[310] Inspired by freethinking women such as Ella Gibson, Victoria Woodhull, Mary Wollstonecraft, Frances Wright, Lucretia Mott, Elizabeth Cady Stanton and Matilda Joslyn Gage, de Cleyre broke from her religious education and "buried her past self".

[311] Pointing out the influence that parents had on their child's early intellectual development, which often resulted in the indoctrination of religious ideas, she emphasised the importance of teaching children critical thinking.

[327] American politician Leonard Abbott placed her alongside Louise Michel and Emma Goldman, who he considered to be "the three great anarchist women of modern times".

[332] Paul Avrich's 1978 book An American Anarchist has been credited as one of the main contributions to scholarship about de Cleyre, who, as of the early 21st century, remained largely unstudied in academic circles.