On the first day of kindergarten at Grace and St. Peter's School, a quiet girl was sitting alone, a new student in a room of boisterous children. • Stephanie Rawlings marched up, introduced herself and took charge: "You're going to play with us and be our friend." • That she was bossy and self-assured from an early age - her mother thinks her first complete sentence was "I did it myself" - might come as no surprise to those who have seen only the public side of Baltimore's next mayor.

Unflappable, soft-spoken and at times seemingly imperious, she has the grave demeanor, if not yet the accomplishments, of her late father and master statesman of Maryland's House of Delegates, Howard P. Rawlings.

But to her family and friends, the publicly aloof Stephanie C. Rawlings-Blake is the same person who reached out to the shy girl of the class, warmhearted and politically precocious. That kindergarten friend, after all, would grow up to become a loyal and longtime aide.

Taking the oath as mayor today caps a frenetic four weeks in which she has mingled with senators and mayors and, last Friday, even met with President Barack Obama - heady stuff even during a normal transition of power. But she also takes office against the backdrop of a City Hall corruption scandal that ousted her predecessor, adding to the tumult.

None of that, though, seems to have pierced her trademark steely exterior. Instead, she enters office with an air of composure, surrounded by many of the same people who have shaped her life to date - even as over the years she has displayed the tough political skills of someone who knows with whom to ally herself and whom to discard along the way.

To those who have seen her self-confidence over the years, it will be no surprise whom or what she plans to fall back on in this next phase.

"The biggest challenge for me is to stay true to what I know to be right in government," Rawlings-Blake, 39, said in a recent interview. "I believe in collaboration. I believe in sharing power. I will be a firm executive, but my challenge is that I won't lose sight of the things that have made me successful."

Late on a recent Friday, Rawlings-Blake joined Police Commissioner Frederick H. Bealefeld III, officers and community activists for a walk through Federal Hill's lively bar district. As the group picked its way through a crowd of people in their 20s in various states of inebriation, Bealefeld approached the owners of a hookah bar - the scene of a stabbing and the source of numerous community complaints - and mildly chastised the owners.

Then Rawlings-Blake, dressed in a black coat with a furry collar, spoke up. "If it's true what I heard," she told the bar owners, "I don't want you to be successful. I want you to close."

Her signature style, a mix of low-key dryness interspersed with blunt pronouncements, has won her allies and enemies.

In contrast to her predecessors - Martin O'Malley, the bandleader likely to take any opportunity to jump on stage, and Sheila Dixon, a former teacher known for speaking her mind - Rawlings-Blake is more reserved. She is by nature serious, if not downright wonky, something that might have served her well, first as a City Council member and then as the legislative body's president.

But as she has neared the much higher-profile mayor's office, she has had to get used to having a half-dozen cameras trained on her while she's thinking through a problem.

Being in the public gaze is difficult, Rawlings-Blake says.

"I don't wear my heart on my sleeve," she said. "It's just not who I am."

The Rawlings-Blake political biography tends to begin with her father, but his legacy is one that from an early age she knew could both help or overshadow her.

"Pete" and Nina Rawlings met while studying at what was then called Morgan State College. Both came from large families led by parents with high expectations. Pete Rawlings, who had spent part of his childhood in public housing, majored in math. Nina Cole was a pre-med student who would become one of the first black women to graduate from the University of Maryland School of Medicine.

Residents of the Ashburton neighborhood, traditionally home to many of the city's most influential African-Americans, the Rawlings family associated with professors, ministers and other leaders. Kurt L. Schmoke, who would later become mayor, lived up the street; his son was good friends with Wendell, the youngest Rawlings child.

Encouraged by leading politicians, including Sen. Verda F. Welcome, Rawlings ran for the House of Delegates when his younger daughter was in elementary school. Stephanie tagged along with her father to meetings, sitting under a desk in The Afro-American newsroom while he discussed politics and visiting the home of Welcome, the first black woman to serve in the state Senate, where she recalls being "awestruck" by the senator's poise and confidence.

The youngster eagerly accompanied her father to pass out leaflets and knock on doors. When other children chose birthday parties with superhero or Barbie themes, she planned an election party - complete with candidates, slates of issues and ballots.