Born in the town of Hampden, Maine, she grew up first in Worcester, Massachusetts. At the age of twelve, she sought refuge with her wealthy grandmother in Boston to get away from her alcoholic parents and abusive father. She was the first child of three born to Joseph Dix and Mary Bigelow, who had deep ancestral roots in Massachusetts Bay Colony. Her father was an itinerant worker. About 1821 Dix opened a school in Boston, which was patronized by well-to-do families. Soon afterward she also began teaching poor and neglected children at home, but she suffered poor health. From 1824 to 1830, she wrote devotional books and stories for children. Her Conversations on Common Things (1824) reached its sixtieth edition by 1869.  In 1831 she established a model school for girls in Boston, operating it until 1836, when she had another health breakdown. In hopes of a cure, in 1836 she traveled to England, where she met the Rathbone family. They invited her as a guest to Greenbank, their ancestral mansion in Liverpool. The Rathbones were Quakers and prominent social reformers. At Greenbank, Dix met their circle of men and women who believed that government should play a direct, active role in social welfare. She was also introduced to the reform movement for care of the mentally ill in Great Britain, known as lunacy reform. Its members were making deep investigations of madhouses and asylums, publishing their studies in reports to the House of Commons.

Reform movements for treatment of the mentally ill were related in this period to other progressive causes: abolitionism, temperance, and voter reforms. After returning to America, in 1840-41 Dix conducted a statewide investigation of care for the insane poor in Massachusetts. In most cases, towns contracted with local individuals to care for mentally ill people who could not care for themselves and lacked family/friends to do so. Unregulated and underfunded, this system resulted in widespread abuse. Dix published the results in a fiery report, a Memorial, to the state legislature. “I proceed, Gentlemen, briefly to call your attention to the present state of Insane Persons confined within this Commonwealth, in cages, stalls, pens! Chained, naked, beaten with rods, and lashed into obedience.” Her lobbying resulted in a bill to expand the state’s mental hospital in Worcester.

During the year 1844 Dix visited all the counties, jails and almshouses in New Jersey in a similar investigation. She prepared a memorial for the New Jersey Legislature, giving a detailed account of her observations and facts. Dix urgently appealed to the legislature to act and appropriate funds to construct a facility for the care and treatment of the insane. She cited a number of cases to emphasize the importance of the state taking responsibility for this class of unfortunates.  She gave as an example a man respected as an legislator, and jurist, who came upon hard times in old age and became insane. Dix found him lying on a small bed in a basement room of the county almshouse, absent necessary comforts. She wrote: “This feeble and depressed old man, a pauper, helpless, lonely, and yet conscious of surrounding circumstances, and not now wholly oblivious of the past — this feeble old man, who was he?” Many members of the legislature knew her pauper jurist. Joseph S. Dodd introduced her report to the Senate on January 23, 1845.

Dodd’s resolution to authorize an asylum passed the following day. The first committee made their report February 25, appealing to the New Jersey legislature to act at once. Some politicians secretly opposed it due to taxes needed to support it. Dix continued to lobby for a facility, writing letters and editorials to build support. During the session she met with legislators and held group meetings in the evening at home. The act of authorization was taken up March 14, 1845, and read for the last time. On March 25, 1845, the bill was passed for the establishment of a state facility.  Dix traveled from New Hampshire to Louisiana, documenting the condition of the poor insane, making reports to state legislatures, and working with committees to draft the enabling legislation and appropriations bills needed. In 1846, Dix traveled to Illinois to study mental illness. While there, she fell ill and spent the winter in Springfield recovering. She submitted a report to the January 1847 legislative session, which adopted legislation to establish Illinois’ first state mental hospital.  In 1848, Dix visited North Carolina, where she again called for reform in the care of mentally ill patients. In 1849, when the (North Carolina) State Medical Society was formed, the legislature authorized construction of an institution in the capital, Raleigh, for the care of mentally ill patients. Named in honor of Dorothea Dix, the hospital opened in 1856. A second state hospital for the mentally ill was authorized in 1875, Broughton State Hospital in Morganton, North Carolina; and ultimately, the Goldsboro Hospital for the Negro Insane was also built in the Piedmont area of the segregated state. Dix had a biased view that mental illness was related to conditions of educated whites, not minorities (Dix, 1847).  She was instrumental in the founding of the first public mental hospital in Pennsylvania, the Harrisburg State Hospital. In 1853, she established its library and reading room.

The culmination of her work was the Bill for the Benefit of the Indigent Insane, legislation to set aside 12,225,000 acres (49,473 km2) of Federal land (10,000,000 acres (40,000 km2) to be used for the benefit of the insane and the remainder for the “blind, deaf, and dumb”). Proceeds from its sale would be distributed to the states to build and maintain asylums. Dix’s land bill passed both houses of the United States Congress; but in 1854, President Franklin Pierce vetoed it, arguing that social welfare was the responsibility of the states. Stung by the defeat of her land bill, in 1854 and 1855 Dix traveled to England and Europe. She reconnected with the Rathbones and conducted investigations of Scotland’s madhouses. This work resulted in formation of the Scottish Lunacy Commission to oversee reforms.  Dix visited the British colony of Nova Scotia in 1853 to study its care of the insane. During her visit she traveled the remote Sable Island to investigate reports of insane patients being abandoned there. Such reports were largely unfounded. While on Sable, Dix assisted in a shipwreck rescue. Upon her return to Boston, she led a successful campaign to send upgraded life-saving equipment to the island.

During the American Civil War, Dix was appointed Superintendent of Army Nurses by the Union Army, beating out Dr. Elizabeth Blackwell. She and others found that the qualities that made her a successful crusader—independence, single-minded zeal—were not effective in managing a large organization of female nurses under crisis conditions in a wide geographic area.  Dix set guidelines for nurse candidates. Volunteers were to be aged 35 to 50 and plain-looking. They were required to wear unhooped black or brown dresses, with no jewelry or cosmetics. Dix wanted to avoid sending vulnerable, attractive young women into the hospitals, where she feared they would be exploited by the men (doctors as well as patients). Dix often fired volunteer nurses she hadn’t personally trained or hired (earning the ire of supporting groups like the United States Sanitary Commission).

At odds with Army doctors, Dix feuded with them over control of medical facilities and the hiring and firing of nurses. Many doctors and surgeons did not want any female nurses in their hospitals. To solve the impasse, the War Department introduced Order No.351 in October 1863. It granted both the Surgeon General (Joseph K. Barnes) and the Superintendent of Army Nurses (Dix) the power to appoint female nurses. However, it gave doctors the power of assigning employees and volunteers to hospitals. This relieved Dix of direct operational responsibility. Meanwhile, her influence was being eclipsed by other prominent women such as Dr. Mary Edwards Walker and Clara Barton. She resigned in August 1865 and later considered this “episode” in her career a failure. Although thousands of Catholic nuns successfully served as Army nurses, Dix distrusted them; her anti-Catholicism undermined her ability to work with Irish and German nuns. She ridiculed them as “robotic and unfeeling.”

But her even-handed caring for Union and Confederate wounded alike, assured her memory in the South. Her nurses provided what was often the only care available in the field to Confederate wounded. Georgeanna Woolsey, a Dix nurse, said, “The surgeon in charge of our camp…looked after all their wounds, which were often in a most shocking state, particularly among the rebels. Every evening and morning they were dressed.” Another Dix nurse, Julia Susan Wheelock, said, “Many of these were Rebels. I could not pass them by neglected. Though enemies, they were nevertheless helpless, suffering human beings.”  When Confederate forces retreated from Gettysburg, they left behind 5,000 wounded soldiers. These were treated by many of Dix’s nurses. Union nurse Cornelia Hancock wrote about the experience: “There are no words in the English language to express the suffering I witnessed today….”

Following the war, she resumed her crusade to improve the care of prisoners, the disabled, and the mentally ill. Her first step was to review the asylums and prisons in the South to evaluate the war damage to their facilities.  In 1881, Dix moved into the New Jersey State Hospital, Morris Plains. The state legislature had designated a suite for her private use as long as she lived. Although an invalid, she carried on correspondence with people from England, Japan, and elsewhere. Dix died on July 17, 1887. She was buried in Mount Auburn Cemetery in Cambridge, Massachusetts.