While attending the Higher School for Girls in Metz, Pfülf developed an interest in social justice and the then-illegal socialist movement.

[4]: 146 Within the SPD, Pfülf held reformist positions close to the moderate wing, accepting Marxist principles but focusing on concrete political work rather than theory.

Her experience as a teacher, during which time she had often loaned money to and bought essentials for impoverished students' families, drove her dedication to political work.

Chairman Erich Mühsam ordered her to leave, but Pfülf refused, declaring: "You'll have to use force to throw me out, because I'm here to represent women's interests."

She was largely unsuccessful in bringing working- and middle-class women together, and Lida Gustava Heymann wrote that socialist men were uncomfortable with Pfülf's organising, which "they felt went right to the heart of things and threatened their sense of authority".

She had sharply criticised Auer for refusing to guarantee women's representation on the provisional council, and he resented her association with the temperance movement.

[4]: 148–149 Pfülf came into further conflict with Erhard Auer over his actions in the aftermath of Kurt Eisner's assassination, and struggled to secure re-nomination for the 1920 election.

[4]: 151  During her time in the Reichstag, she earned respect even from prejudiced colleagues such as Wilhelm Hoegner, who described her as "one of the few intellectually significant women" in parliament and noted the "energy and staying power" she demonstrated in her constituency work.

She condemned male attitudes toward the women's movement, believing that conservative, bourgeois, and socialist men alike feared female suffrage as a threat to their monopoly on power.

In her view, most progressive men still opposed women's advancement on an emotional level, even if they supported it intellectually: "Sexual pride continued to triumph over principle."

The advancement of women within the SPD was painfully slow, and Pfülf typically responded by pointing out the many obstacles they faced within the party.

Pfülf herself was discontent with the situation, but refused to support quotas requiring that women be appointed or nominated in proportion to their total of the party membership.

[4]: 153 Pfülf responded emphatically to the sudden rise of the Nazi Party in the 1930 election, championing the social safety net and labour rights which she saw as key to protecting workers from the economic crisis.

She spoke often and passionately in defence of the republic and social-democratic policies, but was bitterly disappointed by the SPD's decision to tolerate the Brüning government.

She grew weary as the Reichstag's work, to which she had long been dedicated, became irrelevant due to obstruction by extremists and increasing use of presidential decrees.

She was arrested in Weiden in February after giving a speech in which she condemned Nazi violence and censorship, ending by reminding the crowd that a recent Iron Front rally in Berlin had brought together 200,000 people to defy the regime.

She was disgusted as the Reichstag turned into little more than a spectacle of Nazi power, but was persuaded to attend on 23 March and vote against the Enabling Act of 1933 as a show of defiance.

As the situation deteriorated over the following weeks, she helped secure passage out of the country for comrades including Rudolf Breitscheid and his wife Tony, but refused to consider fleeing herself.

Refusing any proposal to accommodate the regime, she opposed a decision by the SPD Reichstag group to back a "peace resolution" put to parliament by Hitler, reportedly "shaking with nervous cramps" while speaking at the party meeting on 17 May.

[4]: 158 Pfülf returned to her home a few days later and received visits from comrades over the following weeks, including Paul Löbe, Louise Schroeder, and Josef Felder.

They implored her to join the brewing underground resistance – Löbe told her that "suicide was no different than abandoning the comrades by going into exile" – but she could not be dissuaded.

In order to protect others from persecution, she had arranged for the mourners to stand silently for only a few minutes before dispersing, and for only a single short statement to be read: "Antonie Pfülf, born on December 14, 1877 in Metz, died on June 8, 1933 in Munich.