In 1896, Katharine Dexter passed MIT’s entrance exams. She wanted to become a surgeon. But like most women who had applied to study a laboratory science before her, she faced additional barriers to entry and had to take three years of prerequisite courses as a “special student” before enrolling for real. Another woman might have walked away, but the 21-year-old Katharine never doubted that she would be one of the first women to earn a biology degree from MIT. She didn’t mind a few years of preparation.

Three years later, in 1899, Katharine Dexter walked through the cool marble halls as a full-fledged student—and soon proved her willingness to challenge authority. Women at MIT were required to wear hats at all times, and fashion favored ones adorned with long, dangling feathers. But that style proved a dangerous combination with the fire and fumes of chemistry labs. To the ire of the department, she not only defied her professors by coming to class hatless but upped the ante, saying that no woman should be required to wear a hat in any class. The chemistry department finally repealed the rule on the grounds of safety.

For Katharine’s first assignment in English composition, she was to write about how she had prepared for MIT. “The Massachusetts Institute of Technology!” she began, in a flourish of playful sarcasm. “How much I had heard about it! How admirable it was said to be … !” She wrote three pages about how she had traveled to Europe to study chemistry, French, and German and then finished three years of prerequisite study at MIT. “[In Europe] I thoroughly studied the German language, at the same time pursuing courses in the ancient languages, such as Greek, Hebrew, and [Sanskrit], in order to be the better prepared for the study of English at the Institute … My previous work seems to be in vain, and I, myself, can only despair,” she wrote. The professor handed her assignment back with the comments “Correct in form; margins admirable; punctuation careful. You quite misunderstood the subject.”

Though her English professor would not have drawn it out of her, Katharine’s determination to attend MIT was born of tragedy. In 1894, her brother, Sam, had succumbed to meningitis while attending Harvard Law School. Four years before that, her father, the esteemed Chicago lawyer Wirt Dexter, had suffered a heart attack and died before her eyes. Devastated by the fatal illnesses of these two beloved men, Katharine vowed to pursue a career in medicine, and she chose what she saw as the best institution to prepare for it.

She was her father’s daughter. Wirt Dexter was an outgoing, idealistic man with a reputation for winning high-profile criminal cases and helping the poor. To him, even the bleakest problems had solutions. After the great Chicago fire of 1871, he became a leader of the Chicago Relief and Aid Society, winning praise for his efficiency as the “almoner” in charge of distributing millions of dollars of donations and allocating coal, mattresses, food, lumber, and blankets to tens of thousands of victims of the fire. He spent more than 10 years in the organization, which lives on today as the Chicago charity Metropolitan Family Services. “One of the most remarkable men of his time,” he was called in the newspapers. But he died at 57, when his daughter was just 14. It’s probably no coincidence that she developed an interest in heart disease, writing an MIT thesis titled “Fatigue of Cardiac Muscles in Reptiles.”

Katharine kept copious notes in colorful marbled notebooks from the MIT Coop, now powdering at the edges. They are the notes of a curious scientist. Her theoretical-biology notebook grapples with the new concepts of evolution, sexual selection, and variation. Her anthropology notes record teachings that natives of the Philippines were “dwarfish abject savages,” evolutionarily closer to monkeys than to white people. She filled page after page with topics in human medicine: the electrical patterns behind dreams, the bony labyrinth of the inner ear, the powers of the thyroid gland.

Right before her final year at MIT, Katharine ran into the handsome, smart, and slightly erratic Stanley McCormick, an old acquaintance from her Chicago youth and—having helped merge his family’s agricultural business with other manufacturers to form International Harvester—the possessor of a hefty fortune. He disarmed her, showering her with flowers and dinners, impressing her with his conversational stamina. “Stanley, please,” Katharine told him when he proposed. “I need to devote all my attention to school. This is just not the time.” But after she earned her bachelor’s degree in biology, they married, and Katharine found herself in a tumultuous relationship instead of medical school.

Always moody, Stanley began suffering from violent, paranoid delusions, and within two years of their wedding, he entered McLean Hospital. Katharine watched in frustration as psychiatric treatment failed to cure him. Convinced his problem was malfunctioning adrenal glands, she fought to get doctors to investigate a link. In 1927, she would establish the Neuroendocrine Research Foundation at Harvard Medical School. But even though Stanley would remain under psychiatric care for the rest of his life, Katharine had no interest in divorce. Remaining his wife protected her from further “male-induced personal disasters,” as she put it. And her life after MIT would be one with no room for such distractions.

Katharine plunged into social issues, beginning with women’s suffrage. She spoke at a Massachusetts rally for that cause in 1909, and by the time the 19th amendment was ratified, in 1920, she had been both treasurer and vice president of the National American Woman Suffrage Association. In 1917, at a Boston trial for a young man charged with distributing pamphlets on female contraception, Katharine met Margaret Sanger, the feminist leader who had been jailed for opening America’s first birth control clinic. When she heard Sanger speak, she knew they had to join forces.

To be free, she believed, women needed some measure of control over their reproductive lives. So she got creative, devising a plan that was elegantly deceptive and grand in scope. In Europe, diaphragms were legal. So Katharine, fluent in French and German, traveled to Europe and posed as a scientist to meet with diaphragm manufacturers. She purchased hundreds of the devices and hired local seamstresses to sew them into dresses, evening gowns, and coats. Then she had the garments wrapped and packed neatly into trunks for shipment. When French customs agents commented on the sheer quantity of clothing, Katharine gushed about how much American women adored French fashion. And if the New York customs service ever rifled through the trunks, agents would have found nothing but slightly puffy dresses in the possession of a bossy socialite, a woman oozing such self-importance and tipping her porters so grandly that no one suspected a thing. Home in the States, she ultimately distributed more than 1,000 diaphragms to Sanger’s clinics.

On January 19, 1947, Stanley died of pneumonia, leaving a $35 million estate. Not long after, Margaret Sanger began hearing rumors that scientists were investigating the possibility of an oral contraceptive. Hoping Katharine would fund the research, Sanger introduced her to the Boston biologist Gregory Pincus, who was studying reproductive hormones. Katharine, who was then 76, wasted no time. At Pincus’s Worcester Foundation for Experimental Biology, she monitored his research, poured in hundreds of thousands of dollars year after year, and helped launch the first human trials. The FDA approved the birth control pill in 1960, seven years before her death.

But Katharine Dexter McCormick’s most direct beneficiaries are women at MIT. One of the Institute’s most generous donors, she funded its first female dormitory—McCormick Hall, named after Stanley. When it opened, in 1963, it provided rooms for 200 women, four times the number MIT had been able to house before. Women now make up nearly half the undergraduate student body—a legacy of Katharine’s lifelong quest to dismantle the barriers that had threatened to keep her from her dreams.