In the freewheeling City Council, where members often crusade on headline-grabbing issues, Jessica Lappin, a freshman member of the Upper East Side, largely keeps out of the limelight.

Ms. Lappin, 32, doesn’t hog press conference podiums, and, when speaking in public, chooses her words almost as carefully as her political causes.

After taking off eight weeks this spring for the birth of her first child, Lucas, Ms. Lappin is back in the City Hall bustle and recently introduced a bill to fine business owners when their employees illegally bike down sidewalks.

It’s a safe issue for her to tackle. Deliverymen who swerve through pedestrian traffic plague her far East Side district, which stretches between 49th and 92nd streets and includes Roosevelt Island. Recently, a friend, who is also a constituent, was knocked over by a bike and broke her hip.

“Some people feel that the symbolic gesture is important,” Ms. Lappin said. “I would rather focus my time and energy on local laws that can have some kind of an impact.”

A newly elected assemblyman of the Upper East Side, Micah Kellner, said Ms. Lappin has shown that she is responsive to the needs of her district. He said she’d lobbied for city funding for a park on the southern tip of Roosevelt Island and negotiated the arrival of a new middle school in the neighborhood.

“When she grabs a hold of something, she is going to take that fight to the end,” he said.

Ms. Lappin — who is chairwoman of the Landmarks, Public Citing, and Maritime Uses Committee — counts negotiating larger budget for the Landmarks Commission for the last two years among her biggest victories in the council.

When elected to the council in 2005, Ms. Lappin already was a familiar face at City Hall. She got her start in politics working as a scheduler to a former speaker of the council, Gifford Miller, and eventually became his district chief of staff. She ran for his seat when he was forced out by term limits.

Her Republican opponent in the council race, Dr. Joel Zinberg, zeroed in on her credentials, criticizing her for being a political insider who lacked real world experience. He offered up his years of work as a surgeon, lawyer, and professor as an alternative to the political machine politicians at City Hall, and won endorsements from the New York Times and Mayor Bloomberg. Ms. Lappin outspent him $222,887 to $99,706, and won 65% of the vote.

Being elected to public office at 30 allowed Ms. Lappin to bring a different perspective to the job than the older members, she said, but she quickly qualified the statement by saying: “It’s hard to know how different.”

Unlike many other council members, who are reachable virtually day and night, Ms. Lappin maintains a strict line between work and her personal life. She objected to The New York Sun’s initial request to photograph her with her son, abdicating on the condition that it was clear the photograph was taken on a weekend.

“One of the important things to me is having boundaries. That’s part of how I make it all work,” she said.

Her poise and drive may come from her years as a competitive figure skater when she was growing up in New York. She was on the ice each morning at 5:45 a.m. at Sky Rink on the Far West Side, skating for two to three hours before school. During high school summers, she trained in Sun Valley, Idaho, practicing for five hours a day.

“She’s highly driven and highly motivated,” another council member of the East Side, Daniel Garodnick, 35, said. “She knows how to do all of the things in her life really, really well.”

Ms. Lappin was born in Brooklyn and grew up near Gramercy Park, attending the United Nations International School before going to Stuyvesant High School. She graduated from Georgetown University in 1997.

Her father was an accountant and her mother, now the chairwoman and chief investment officer of Gramercy Capital Management Corporation, worked on Wall Street. In 2003, Ms. Lappin married Andrew Wuertele, the chief operating officer of a Manhattan radiology practice, East River Medical Imaging.

Ms. Lappin’s political ambitions, however, may not take her as far as she wants to go. She said she is interested in becoming the next council speaker, but in conversations with council members and other political observers, she doesn’t come up as a potential successor to Speaker Christine Quinn.

If re-elected, however, she still could land a leadership position. In 2009, 36 council members face term limits, clearing the way for Ms. Lappin and other first-term members to fill top council posts. In the meantime, she is drawing on her experience as a young mother by drafting a bill to create tax incentives for businesses to provide childcare. Having her son has changed the way she sees and interacts with the city, she said.

“I certainly didn’t use the parks as much as I do now,” she said. “And I was never in the playground.”