Rosa Parks was born Rosa Louise McCauley in Tuskegee, Alabama on February 4, 1913, to James McCauley and Leona Edwards, respectively a carpenter and a teacher, and was of African-American, Cherokee-Creek,and Scots-Irish ancestry. Rosa Park's great grandfather was a Scotch-Irishman. She was small, even for a child, and she suffered poor health and had chronic tonsillitis. When her parents separated, she moved with her mother to Pine Level, just outside Montgomery, Alabama. There she grew up on a farm with her maternal grandparents, mother, and younger brother Sylvester, and began her lifelong membership in the African Methodist Episcopal Church. She was homeschooled by her mother until she was eleven, then enrolled at the Industrial School for Girls in Montgomery where she took academic and vocational courses. Parks then went on to a laboratory school set up by the Alabama State Teachers College for Negroes for secondary education but was forced to drop out to care for her grandmother, and later for her mother, after they became ill.

Under Jim Crow laws, black and white people were segregated in virtually every aspect of daily life in the South, including public transportation. Bus and train companies did not provide separate vehicles for the different races but did enforce seating policies that allocated separate sections for blacks and whites. School bus transportation, however, was unavailable in any form for black schoolchildren in the South. Parks recalled going to elementary school in Pine Level, where school buses took white students to their new school and black students had to walk to theirs: "I'd see the bus pass every day… But to me, that was a way of life; we had no choice but to accept what was the custom. The bus was among the first ways I realized there was a black world and a white world."

Although Parks' autobiography recounts that some of her earliest memories are of the kindness of white strangers, her situation made it impossible to ignore racism. When the Ku Klux Klan marched down the street in front of her house, Parks recalls her grandfather guarding the front door with a shotgun. The Montgomery Industrial School, founded and staffed by white northerners for black children, was burned twice by arsonists, and its faculty was ostracized by the white community.

In 1932, Rosa married Raymond Parks, a barber from Montgomery, at her mother's house. Raymond was a member of the National Association for the Advancement of Colored People (NAACP), at the time collecting money to support the Scottsboro Boys, a group of black men falsely accused of raping two white women. After her marriage, Rosa took numerous jobs, ranging from domestic worker to hospital aide. At her husband's urging, she finished her high school studies in 1933, at a time when less than 7% of African Americans had a high school diploma. Despite the Jim Crow laws that made political participation by black people difficult, she succeeded in registering to vote on her third try.

In December 1943, Parks became active in the Civil Rights Movement, joined the Montgomery chapter of the NAACP, and was elected volunteer secretary to its president, Edgar Nixon. Of her position, she later said, "I was the only woman there, and they needed a secretary, and I was too timid to say no." She continued as secretary until 1957. In the 1940s, Parks and her husband were also members of the Voters' League. Sometime soon after 1944, she held a brief job at Maxwell Air Force Base, a federally owned area where racial segregation was not allowed, and rode on an integrated trolley. Speaking to her biographer, Parks noted, "You might just say Maxwell opened my eyes up." Parks also worked as a housekeeper and seamstress for a white couple, Clifford and Virginia Durr. The politically liberal Durrs became her friends and encouraged Parks to attend—and eventually helped sponsor her—at the Highlander Folk School, an education center for workers' rights and racial equality in Monteagle, Tennessee, in the summer of 1955.

Like many black people, Parks was deeply moved by the brutal murder of Emmett Till in August 1955. On November 27, 1955 — only four days before she refused to give up her seat—she later recalled that she had attended a mass meeting in Montgomery which focused on this case as well as the recent murders of George W. Lee and Lamar Smith. The featured speaker at the meeting was T.R.M. Howard, a black civil rights leader from Mississippi who headed the Regional Council of Negro Leadership. People also said that Rosa Parks was "Sweet and soft spoken but made a statement that screamed so loud."

After a day at work at Montgomery Fair department store, Parks boarded the Cleveland Avenue bus at around 6 p.m., Thursday, December 1, 1955, in downtown Montgomery. She paid her fare and sat in an empty seat in the first row of back seats reserved for blacks in the "colored" section, which was near the middle of the bus and directly behind the ten seats reserved for white passengers. Initially, she had not noticed that the bus driver was the same man, James F. Blake, who had left her in the rain in 1943. As the bus traveled along its regular route, all of the white-only seats in the bus filled up. The bus reached the third stop in front of the Empire Theater, and several white passengers boarded.

In 1900, Montgomery had passed a city ordinance for the purpose of segregating passengers by race. Conductors were given the power to assign seats to accomplish that purpose; however, no passengers would be required to move or give up their seat and stand if the bus was crowded and no other seats were available. Over time and by custom, however, Montgomery bus drivers had adopted the practice of requiring black riders to move whenever there were no white only seats left.

So, following standard practice, bus driver Blake noted that the front of the bus was filled with white passengers and there were two or three men standing, and thus moved the "colored" section sign behind Parks and demanded that four black people give up their seats in the middle section so that the white passengers could sit. Years later, in recalling the events of the day, Parks said, "When that white driver stepped back toward us, when he waved his hand and ordered us up and out of our seats, I felt a determination cover my body like a quilt on a winter night."

By Parks' account, Blake said, "Y'all better make it light on yourselves and let me have those seats." Three of them complied. Parks said, "The driver wanted us to stand up, the four of us. We didn't move at the beginning, but he says, 'Let me have these seats.' And the other three people moved, but I didn't." The black man sitting next to her gave up his seat. Parks moved, but toward the window seat; she did not get up to move to the newly repositioned colored section. Blake then said, "Why don't you stand up?" Parks responded, "I don't think I should have to stand up." Blake called the police to arrest Parks. When recalling the incident for Eyes on the Prize, a 1987 public television series on the Civil Rights Movement, Parks said, "When he saw me still sitting, he asked if I was going to stand up, and I said, 'No, I'm not.' And he said, 'Well, if you don't stand up, I'm going to have to call the police and have you arrested.' I said, 'You may do that.'"

During a 1956 radio interview with Sydney Rogers in West Oakland several months after her arrest, when asked why she had decided not to vacate her bus seat, Parks said, "I would have to know for once and for all what rights I had as a human being and a citizen of Montgomery, Alabama."

"People always say that I didn't give up my seat because I was tired, but that isn't true. I was not tired physically, or no more tired than I usually was at the end of a working day. I was not old, although some people have an image of me as being old then. I was forty-two. No, the only tired I was, was tired of giving in."

When Parks refused to give up her seat, a police officer arrested her. As the officer took her away, she recalled that she asked, "Why do you push us around?" The officer's response as she remembered it was, "I don't know, but the law's the law, and you're under arrest." She later said, "I only knew that, as I was being arrested, that it was the very last time that I would ever ride in humiliation of this kind."

Parks was charged with a violation of Chapter 6, Section 11 segregation law of the Montgomery City code, even though she technically had not taken up a white-only seat—she had been in a colored section. E.D. Nixon and Clifford Durr bailed Parks out of jail the evening of December 1.

That evening, Nixon conferred with Alabama State College professor Jo Ann Robinson about Parks' case. Robinson, a member of the Women's Political Council (WPC), stayed up all night mimeographing over 35,000 handbills announcing a bus boycott. The Women's Political Council was the first group to officially endorse the boycott.

On Sunday, December 4, 1955, plans for the Montgomery Bus Boycott were announced at black churches in the area, and a front-page article in The Montgomery Advertiser helped spread the word. At a church rally that night, attendees unanimously agreed to continue the boycott until they were treated with the level of courtesy they expected, until black drivers were hired, and until seating in the middle of the bus was handled on a first-come basis.

Four days later, Parks was tried on charges of disorderly conduct and violating a local ordinance. The trial lasted 30 minutes. Parks was found guilty and fined $10, plus $4 in court costs. Parks appealed her conviction and formally challenged the legality of racial segregation. In a 1992 interview with National Public Radio's Lynn Neary, Parks recalled:

"I did not want to be mistreated, I did not want to be deprived of a seat that I had paid for. It was just time... there was opportunity for me to take a stand to express the way I felt about being treated in that manner. I had not planned to get arrested. I had plenty to do without having to end up in jail. But when I had to face that decision, I didn't hesitate to do so because I felt that we had endured that too long. The more we gave in, the more we complied with that kind of treatment, the more oppressive it became."

On Monday, December 5, 1955, after the success of the one-day boycott, a group of 16 to 18 people gathered at the Mt. Zion AME Zion Church to discuss boycott strategies. The group agreed that a new organization was needed to lead the boycott effort if it were to continue. Rev. Ralph David Abernathy suggested the name "Montgomery Improvement Association" (MIA). The name was adopted, and the MIA was formed. Its members elected as their president a relative newcomer to Montgomery, a young and mostly unknown minister of Dexter Avenue Baptist Church, Dr. Martin Luther King, Jr.

That Monday night, 50 leaders of the African American community gathered to discuss the proper actions to be taken in response to Parks' arrest. E.D. Nixon said, "My God, look what segregation has put in my hands!" Parks was the ideal plaintiff for a test case against city and state segregation laws. While the 15-year-old Claudette Colvin, unwed and pregnant, had been deemed unacceptable to be the center of a civil rights mobilization, King stated that, "Mrs. Parks, on the other hand, was regarded as one of the finest citizens of Montgomery—not one of the finest Negro citizens, but one of the finest citizens of Montgomery." Parks was securely married and employed, possessed a quiet and dignified demeanor, and was politically savvy.

The day of Parks' trial — Monday, December 5, 1955 — the WPC distributed the 35,000 leaflets. The handbill read, "We are…asking every Negro to stay off the buses Monday in protest of the arrest and trial . . . You can afford to stay out of school for one day. If you work, take a cab, or walk. But please, children and grown-ups, don't ride the bus at all on Monday. Please stay off the buses Monday."

It rained that day, but the black community persevered in their boycott. Some rode in carpools, while others traveled in black-operated cabs that charged the same fare as the bus, 10 cents. Most of the remainder of the 40,000 black commuters walked, some as far as 20 miles (30 km). In the end, the boycott lasted for 382 days. Dozens of public buses stood idle for months, severely damaging the bus transit company's finances, until the law requiring segregation on public buses was lifted.

Some segregationists retaliated with terrorism. Black churches were burned or dynamited. Martin Luther King's home was bombed in the early morning hours of January 30, 1956, and E.D. Nixon's home was also attacked. However, the black community's bus boycott marked one of the largest and most successful mass movements against racial segregation. It sparked many other protests, and it catapulted King to the forefront of the Civil Rights Movement.

Through her role in sparking the boycott, Rosa Parks played an important part in internationalizing the awareness of the plight of African Americans and the civil rights struggle. King wrote in his 1958 book Stride Toward Freedom that Parks' arrest was the precipitating factor, rather than the cause, of the protest: "The cause lay deep in the record of similar injustices…. Actually, no one can understand the action of Mrs. Parks unless he realizes that eventually the cup of endurance runs over, and the human personality cries out, 'I can take it no longer.'"

The Montgomery bus boycott was also the inspiration for the bus boycott in the township of Alexandria, Eastern Cape of South Africa which was one of the key events in the radicalization of the black majority of that country under the leadership of the African National Congress.

After her arrest, Parks became an icon of the Civil Rights Movement but suffered hardships as a result. She lost her job at the department store, and her husband quit his job after his boss forbade him from talking about his wife or the legal case. Parks traveled and spoke extensively. In 1957, Raymond and Rosa Parks left Montgomery for Hampton, Virginia; mostly because she was unable to find work, but also because of disagreements with King and other leaders of Montgomery's struggling civil rights movement. In Hampton, she found a job as a hostess in an inn at black Hampton Institute. Later that year, after the urging of her younger brother Sylvester, Rosa, her husband Raymond, and her mother Leona McCauley, moved to Detroit, Michigan.

Parks worked as a seamstress until 1965 when African-American U.S. Representative John Conyers hired her as a secretary and receptionist for his congressional office in Detroit. She held this position until she retired in 1988. In a telephone interview with CNN on October 24, 2005, Conyers recalled, "You treated her with deference because she was so quiet, so serene—just a very special person…. There is only one Rosa Parks." Later in life, Parks also served as a member of the Board of Advocates of the Planned Parenthood Federation of America.

Rosa Parks and Elaine Eason Steele co-founded the Rosa and Raymond Parks Institute for Self Development in February 1987, in honor of Rosa's husband, who died from cancer in 1977. The institute runs the "Pathways to Freedom" bus tours, which introduce young people to important civil rights and Underground Railroad sites throughout the country.

In 1992, Parks published Rosa Parks: My Story, an autobiography aimed at younger readers which details her life leading up to her decision not to give up her seat. In 1995, she published her memoirs, titled Quiet Strength, which focuses on the role that her faith had played in her life.

On August 30, 1994, Joseph Skipper, an African-American drug addict, attacked 81-year-old Parks in her home. The incident sparked outrage throughout America. After his arrest, Skipper said that he had not known he was in Parks' home but recognized her after entering. Skipper asked, "Hey, aren't you Rosa Parks?" to which she replied, "Yes." She handed him $3 when he demanded money, and an additional $50 when he demanded more. Before fleeing, Skipper struck Parks in the face. Skipper was arrested and charged with various breaking and entering offenses against Parks and other neighborhood victims. He admitted guilt and, on August 8, 1995, was sentenced to eight to 15 years in prison.

A comedic scene in the 2002 film Barbershop featured a cantankerous barber, played by Cedric the Entertainer, arguing with co-workers and shop patrons that other African Americans before Parks had resisted giving up their seats in defiance of Jim Crow laws, and that she had received undeserved fame because of her status as an NAACP secretary. Activists Jesse Jackson and Al Sharpton launched a boycott against the film, contending it was "disrespectful", but NAACP president Kweisi Mfume stated he thought the controversy was "overblown." The scene also offended Parks, who boycotted the NAACP 2003 Image Awards ceremony, which Cedric hosted. "Barbershop" received nominations in four awards categories that, including a "Best Supporting Actor in a Motion Picture" nomination for Cedric. He did not win in that category, however, but won an award for his work as a supporting actor in the television series The Proud Family.

Rosa Parks resided in Detroit until she died at the age of ninety-two on October 24, 2005, about 19:00 EDT, in her apartment on the east side of the city. She had been diagnosed the previous year with progressive dementia.

City officials in Montgomery and Detroit announced on October 27, 2005 that the front seats of their city buses would be reserved with black ribbons in honor of Parks until her funeral. Parks' coffin was flown to Montgomery and taken in a horse-drawn hearse to the St. Paul African Methodist Episcopal (AME) church, where she lay in repose at the altar, dressed in the uniform of a church deaconess, on October 29, 2005. A memorial service was held there the following morning, and one of the speakers, Secretary of State Condoleezza Rice, said that if it had not been for Rosa Parks, she would probably have never become the Secretary of State. In the evening the casket was transported to Washington, D.C., and taken, aboard a bus similar to the one in which she made her protest, to lie in honor in the U.S. Capitol Rotunda (making her the first woman and second African American ever to receive this honor). An estimated 50,000 people viewed the casket there, and the event was broadcast on television on October 31, 2005. This was followed by another memorial service at a different St. Paul AME church in Washington on the afternoon of October 31, 2005. For two days, she lay in repose at the Charles H. Wright Museum of African American History in Detroit.

Parks' funeral service, seven hours long, was held on Wednesday, November 2, 2005, at the Greater Grace Temple Church. After the funeral service, an honor guard from the Michigan National Guard laid the U.S. flag over the casket and carried it to a horse-drawn hearse, which had been intended to carry it, in daylight, to the cemetery. As the hearse passed the thousands of people who had turned out to view the procession, many clapped and released white balloons. Rosa was interred between her husband and mother at Detroit's Woodlawn Cemetery in the chapel's mausoleum. (The chapel was renamed the Rosa L. Parks Freedom Chapel just after her death.) Parks had previously prepared and placed a headstone on the selected location with the inscription "Rosa L. Parks, wife, 1913–".