O'Reilly was deeply involved in the New York Shirtwaist Strike, the Uprising of the 20,000. In part in reaction to what she thought was the betrayal of wealthy women supporters of the shirtwaist workers, in 1910, O'Reilly became a member of the Socialist Party of New York. Nonetheless, she remained a dedicated supporter of women's rights and woman suffrage. In 1912 O’Reilly founded the Wage Earners Suffrage League, the "industrial wing" of the Woman Suffrage Party, and had called for more fair wages which many upper-class women were not as likely to support. O’Reilly had an ‘equal pay for equal work’ plan for the movement after they had made a dent in their efforts. O'Reilly served as the president of the Wage Earner’s Suffrage League from 1911 to 1912. In this capacity she served as a volunteer investigator to the Triangle Shirtwaist Factory fire of 1911. In 1912, O'Reilly was appointed as the Chair of the Industrial Committee of the New York City Women Suffrage Party. Nicknamed as 'the agitator,' O'Reilly worked to empower the voice of women workers, rather than supporting their interests on the public platform alone. When speaking about disenfranchised women workers, she would frequently refer to them as ‘intelligent women’ and ‘thinking women’ because that is how O’Reilly perceived them, despite the patriarchal social-norms that at the time did not think as highly of the women. This was made evident throughout her speeches, but notably in her 1896 speech titled "Organization" in which she put heavy emphasis on providing the unprivileged class of workers a sense of class-consciousness against the big industries, which O’Reilly felt had exploited their hard labor. In 1915, O'Reilly served as the Trade Union Delegate to the International Congress of Women. At this time O'Reilly was 45 years old and she began to suffer from the early stages of heart disease which would slowly trump her ability to be an energetic activist. In 1919, O'Reilly again served as the Trade Union Delegate, this time to the International Congress for Working Women. In 1925 and 1926, O'Reilly taught courses at New York's New School for Social Research; these courses were on topics related to 'the theory of the labor movement'. In 1927, O'Reilly died at the age of 56 due to heart disease. Irish-American Female Leadership When Irish nationalism gained prominence in the U.S in the early 1880s, it enabled Irish-American women their