As Catherine Donnelly climbed the stairs to her dorm room at Princeton University over a quarter-century ago, the Louisiana freshman felt ready for whatever lay ahead. But then she met Michelle. Her full name was Michelle LaVaughn Robinson. She was so tall that her head seemed to brush the sloping ceiling of the cramped fourth-floor room. She was Donnelly's new roommate. And she was black. Well, this was new. Growing up in the South, Donnelly had gone to school with a handful of black classmates, but living together was quite another thing. Donnelly quickly warmed to Robinson, with her big sense of humor and riveting stories. But she was worried that her mother, who Donnelly said had grown up in a racist family, would not react well. She was right. When Donnelly's mother, now 71, learned the race of her daughter's roommate , she was beside herself. She called alumni friends to object. And the next morning she marched into the student housing office. "I said I need to get my daughter's room changed right away," recalled Alice Brown, a retired schoolteacher, who has since come to regret her reaction. "I called my own mother and she said, 'Take Catherine out of school immediately. Bring her home.' I was very upset about the whole thing." For 17-year-old Robinson - who is now Michelle Obama and the first African-American woman to face the real prospect of becoming first lady - the incident was a stunning beginning to a formative chapter in her life. It was a time when her views on race and American culture began to coalesce - views that have helped make her a compelling figure but also somewhat of a lightning rod during the campaign. Just last week the Barack Obama campaign took on an apparently baseless rumor that she had once been taped talking of white Americans as "whitey." Obama says she did not know about Alice Brown's actions until several weeks ago. But she wonders now if the incident might explain in part why she and Brown's daughter did not become better friends. "We were never close," Obama said in an e-mail. "But sometimes that's the thing you sense, that there's something that's there, but it's often unspoken." At the time Obama entered Princeton in 1981, the Ivy League campus was largely, if unofficially, segregated socially and Obama found her years there marked by questions about race and loyalty - much the same questions she and her husband often face today. Then, as now, Obama's focus was on overcoming differences rather than igniting them. The lesson she finds in the roommate incident is one of hope - Alice Brown is now considering casting her vote for Barack Obama.

"What it demonstrated was the growth that this parent had," Obama wrote. "What that told me is that, yes, the problems we face in this nation around race are real . . . but we also have to remember that people change and they grow." Michelle Obama has often been cast as the more adamant half of the Obama household, when it comes to racial matters, and some have traced this thread to her Princeton years. But she was hardly a campus activist. Instead, she pursued quieter means of change characteristic of her practical nature, according to classmates with whom she remains close. In her efforts to understand the lot of black students, this determined young woman with the big hair and trademark strand of pearls attended meetings with school administrators about the African- American Studies department, helped bring black alumni to campus to address students, and worked afternoons in the school's Third World Center. It was, according to several professors and friends close to her, a critical passage in her life. "Princeton was a real crossroads of identity for Michelle," said Harvard Law School professor Charles J. Ogletree, who was her law school adviser and now works with the Obama campaign. "The question was whether I retain my identity given by my African-American parents, or whether the education from an elite university has transformed me into something different than what they made me. By the time she got to Harvard she had answered the question. She could be both brilliant and black." Search for racial identity

Obama's questions became, in part, the subject of her senior thesis, called "Princeton-Educated Blacks and The Black Community." Much has been made in the blogosphere of Obama's observation in that work: "My experiences at Princeton have made me far more aware of my 'Blackness' than ever before . . . Regardless of the circumstances under which I interact with Whites at Princeton, it often seems as if, to them, I will always be Black first and a student second." But her 1985 thesis is not just about her own experience, but also examines larger issues of racial identity. The thesis had been embargoed until after the presidential election, but when the campaign came under criticism, it was released in February. "Michelle's central question was what good does a Princeton education do for the black community," recalled Howard Taylor, sociology professor emeritus, and former chairman of the Center for African American Studies. "What will it do for me? Will it separate me from the black community?" Princeton in the early 1980s was not an easy place to be black. For young Michelle Robinson, reared on the South Side of Chicago and the daughter of a municipal pump operator, it was "a new frontier," as Katie McCormick Lelyveld, Obama's director of communications, described it. Long regarded as the most conservative of the Ivy League schools, its social scene was dominated by elite "eating clubs" where blacks sometimes worked but were rarely members. Many blacks socialized largely among themselves, according to some students, including the school's director of communications, Lauren Robinson-Brown, a classmate of Obama's.

"We ate together. We partied together. We were each others' support system," she said. When Obama entered Princeton, she was one of 94 black students in a class of 1,141. Her transition from her family's one-bedroom urban apartment to the exclusive suburban campus was made somewhat easier by the fact that her brother Craig Robinson had arrived there two years earlier. Robinson, now the head basketball coach at Oregon State University, was a star basketball player who had been recruited to the campus and his success opened many doors for his younger sister. But still, the veil of race hung heavy. Despite her mother's opposition, Catherine Donnelly was drawn to her new roommate, one of two young women with whom she shared the low-ceilinged room in Pyne Hall. She recalled that Obama, whom many called "Miche," "had these beautiful long-fingered hands that she used to tell great stories with. I loved her hands." But when another room became available the following semester, Donnelly moved out. She says it was not because of her mother's racial concerns, but because the new room was larger. Once she moved out, she said she and Obama rarely spoke, even when they passed each other on campus. "Michelle early on began to hang out with other black students," said Donnelly, now a lawyer in Palmetto, Ga. "Princeton was just a very segregated place. I wish now that I had pushed harder to be friends, but by the same token she did not invite me to do things either." Obama herself often felt stigmatized on campus. In her thesis, she wrote that at Princeton, "No matter how liberal and open minded some of my White professors and classmates try to be toward me, I sometimes feel like a visitor on campus; as if I really don't belong." Obama and her friends talked about the racial situation on campus a lot. "But Michelle kind of stayed away from the fray," recalled Lisa F. Rawlings, a classmate who is now a program director at Prince George's Community College in Maryland. Asked if Obama experienced incidents of racism, Lelyveld said in an e-mail that, "So many years down the line, she [Obama] can't say for certain whether there were any specific incidents." Lelyveld initially said that Obama did not remember her freshman roommate. But several of Obama's African-American classmates say they found the campus was as racially fragmented as it was elitist, and some white students agree. Hilary Beard, a friend of Obama's who is African-American and was a class ahead, recalls, "A lot of white students there had never been around black students. . . . They would want to touch my hair." And Rawlings says, "I cannot tell you the number of times I was called 'Brown Sugar.' "

While many found such incidents disturbing, Obama's brother, Craig Robinson, says that few got up in arms about it. "We all viewed it as what you needed to do, to do business there," said Robinson. "You had to put up with certain things." By her second year, Obama had settled in with three roommates of color in a suite of sparely furnished rooms. She quickly gained a reputation for her vast collection of Stevie Wonder records. An early riser, she was also known for her stylish appearance. "Michelle was always fashionably dressed, even on a budget," remembers Angela Acree, Obama's roommate for three years and now a Washington, D.C., lawyer. "You wouldn't catch her in sweats, even back then." But mostly Obama was recognized for her commitment to her studies. Part of it was the rigor of the school. And part of it was the expectations that she - like many black students who were the first in their family to go to college - knew awaited her back home. "Michelle and Craig spoke a lot about their parents," said Beard. "She was going to succeed for them as much as herself." Obama, who majored in sociology with a minor in African-American studies, dedicated her thesis to, "Mom, Dad, Craig and all of my special friends. Thank you for loving me and always making me feel good about myself." Although Obama had friends who were both black and white, her social world revolved around several of the black organizations on campus, as it did for many other black students. Obama was a member of the Organization of Black Unity, a primary resource for black students on campus which arranged speakers and programs. There was also a Black Thoughts Table, a popular discussion group about current affairs and race. Obama also took part in two fashion shows that were sponsored largely by black student groups. In one devoted to the Ethiopian Relief Fund in 1985, and dubbed "Secret Fantasy," she modeled a sleeveless red velvet ball gown. In the other, which benefited a local after-school program, she was clad in a yellow Caribbean peasant skirt. Lelyveld said that Obama does not recall the events, but the organizers remember her vividly. Karen Jackson Ruffin, who designed the dresses Obama wore, recalled that she asked Obama to participate, "because she is so tall and carries herself so well. Michelle is very mellow and she said, 'Sure.' " A cultural home

One of the issues debated among black students at the time was whether they could partake in white-dominated schools and careers and still remain connected to the black community. "The question was were you a traitor to your race to go to a white-dominated school at all," said Steve Dawson, a Princeton alumnus and the former head of the Association of Black Princeton Alumni. "Michelle had crossed that threshold in going to Princeton. But she was concerned as she considered law school, is it still an OK thing to do?"