She began her career at a mental hospital in Torrance, Pennsylvania, where she imposed changes to rectify the persistent mistreatment of staff and patients.

She also led a demonstration during a United States Senate subcommittee meeting that was credited with restarting hearings on the Equal Rights Amendment (ERA).

[3] Heide was raised Lutheran and regularly attended youth group, but she left the church as a teenager after learning that women could not be ordained.

[8] She graduated from Connellsville High School in June 1938,[4] and received a scholarship to Seton Hill University, but her parents refused to allow her to attend as they were unable to afford to pay for college for all the children.

[1][2] Instead, she continued to play with the Fayette Shamrocks and lived at home, picking up odd jobs at a department store or selling products door-to-door.

She spoke to one of her fellow attendants about being stalked by a woman who intended to kill her, which her colleague recognised as a symptom of her increasing stress and frustration.

[2] When Eugene was sent to Fort Benning, Georgia, Heide worked as a night supervisor and sociology researcher at the Phoenix City Hospital.

[2] She was involved in the civil rights movement, the parent–teacher association (PTA), and chaired the Home Health Care Advisory Committee of the Miners Clinic.

[2][23] Heide remained active in the New Kensington chapter of the NAACP, alongside her work with the American Institutes for Research and beginning to study for her doctorate at the University of Pittsburgh, although she interrupted her degree to focus on her activist causes.

The organization chose Stouffer's Restaurant in Oakland, where men were able to sit in a private dining room while women had to eat in the public area.

The sit-in was organized by Heide to coincide with the campaign to make gender a protected characteristic in the anti-discrimination ordinance covering employment, housing, and public accommodations.

[29] This complaint challenged the practice of the newspaper of separating help wanted advertisements by those employers seeking women or men in columns with different headings.

[30] The Commission upheld the complaint under the ordinance and the newspaper filed suit, claiming that the restriction violated its rights under the First Amendment to freedom of the press.

[2] The company had a policy that de facto prohibited women from certain positions by imposing a restriction that required employees to lift packages over 30 pounds (14 kg).

[32] On February 17, 1970, Heide and Jean Witter led a group of twenty chapter members to disrupt a hearing on allowing eighteen-year-olds to vote, which was being held by a subcommittee of the United States Senate on constitutional amendments.

The women held up signs and Heide gave a speech demanding that the Senate take action to pass the Equal Rights Amendment (ERA).

[6][33] After the disruption, the women met privately with Senator Birch Bayh who agreed to hold hearings on the ERA later in the year, and later credited their demonstration with convincing him to act on the issue.

The Equal Employment Opportunity Commission (EEOC), at NOW's urging, conducted an investigation that found that women employees were not working in all available jobs, which caused them to lose $422 million (equivalent to $3.17 billion in 2023).

In 1972, Heide and other members of NOW met with Robert Lilley, the president of AT&T, to discuss the EEOC report and to challenge the inadequacy of the proposed affirmative action plan.

She also urged NOW members to refuse to join Common Cause, a lobbying organization, until it expressed its support for the ERA; this finally happened after a meeting between John Gardner and Heide, Aileen Hernandez, Ann Scott and Carol Burris.

Heide also convinced the LWV, the American Nurses Association (ANA), the AFL–CIO, and the Leadership Conference on Human Rights to support the ERA.

Heide, Jo Ann Evansgardner, Patricia Hill Burnett and Rona Fields collaborated on an international conference on June 1, 1973, which brought together more than 300 women from 27 countries.

She flew over with Sandy Byrd, Judy Pickering and Betty Spaulding and the four women toured the country for ten days, which concluded with Heide being presented with the key to the city of Stockholm.

Heide had also previously assisted with the founding of the National Women's Political Caucus in 1971 and she served on the Policy Council until 1974 and on the Advisory Board until 1977.

[12][56] She worked as a visiting professor for half a decade, beginning her teaching career at Wellesley College and the University of Massachusetts in 1974 and leaving the institutions in 1975 and 1976 respectively.