In a crowded Takoma Park family room on election night, four dozen people of all hues and accents huddled around a television monitoring the returns, hugging and cheering Thomas Perez and watching history unfold.

The diverse gathering of campaign volunteers and friends -- whites, blacks, Latinos, Asian Americans and Native Americans -- was indicative of the multicultural coalition that helped Perez become the first Latino to win a seat on the Montgomery County Council.

"Look around," the council member-elect said proudly. "This is a victory for progressive leadership in Montgomery County -- this is the future of the Democratic Party in Maryland."

Perez takes office during a period of remarkable demographic transformation. Montgomery's minority population stands at 40 percent, and its Latino population is the largest in the state. In District 5, he will represent the county's most heterogenous neighborhoods, from Silver Spring and Takoma Park to Wheaton and Kensington. One in five district residents is Latino, many of them recent immigrants.

A first-generation Dominican American, Democrat Perez reached out to the burgeoning community by knocking on the doors of hundreds of Latino residents, calling their homes, mailing bilingual campaign literature and using Spanish-language media to communicate his positions.

In the September primary, he fended off four opponents, including one supported aggressively by County Executive Douglas M. Duncan (D). On Tuesday, with 77 percent of the vote, he claimed a landslide victory against Republican Dennis E. Walsh.

"It's the first time . . . that Latinos can see a person on the County Council who is progressive, who is Latino and who cares about them," said Gustavo A. Torres, executive director of nonprofit service agency Casa de Maryland. "It's historic because Latinos came out to vote -- many for the very first time -- and it made a difference in the election of Tom Perez."

Despite the county's increasing diversity, the council is not becoming more diverse. Perez will be its sole minority member after next month's swearing-in because Isiah Leggett, an at-large Democratic member and the council's first and only African American member, is departing after 16 years.

Leggett, who campaigned for Perez, said he believes he is the right person for the times. "Tom has keen leadership skills, and he understands the community," Leggett said. "It's a community with a great deal of challenges."

The 41-year-old civil rights lawyer was raised in a middle-class family in Buffalo, N.Y., where his parents, Rafael and Grace, settled after leaving the Dominican Republic. His father was a doctor and worked in a Veterans Administration hospital after a tour in the Army. His mother was a homemaker, though after her husband died when Thomas was 12, she earned a degree in English literature from the University of Buffalo.

His parents instilled in Perez the importance of public service. "The United States gave them opportunities even though this was their adopted homeland," he said. "They would tell me how much they loved this country and how it was important for me to be involved."

A graduate of Brown University, Harvard Law School and the John F. Kennedy School of Government, Perez has spent his career in public service. For six years, he worked as a federal prosecutor in the civil rights division of the Justice Department. He served as director of the civil rights office at the Department of Health and Human Services when Donna E. Shalala was its secretary under President Bill Clinton.

Perez is president of the board of Casa de Maryland, a senior technical adviser to the Latino Health Initiative of Montgomery County and an assistant law professor at the University of Maryland.

Perez, who has lived in Takoma Park for eight years, said he would advocate on the council for more affordable housing, push for jobs for low-income residents, make sure schools offer quality education to all students and help poor residents obtain access to social services.

He does not support Duncan's plan to build the intercounty connector, a highway that would link Interstates 95 and 270, which he feels is an excessively costly proposal.

Instead, his transportation priority will be construction of the Inner Purple Line, the proposed light-rail Metro route linking Bethesda and Silver Spring to Langley Park, College Park and New Carrollton. District 5's low-income residents, who depend heavily on public transit to reach work and child care, need that project, he said.

But the most challenging aspect of his new political career, as he sees it, will be juggling council duties with family responsibilities. Perez and his wife, Ann Marie Staudenmaier, have three children ages 5 months to 6 years.

"Certainly, Tom's election to the council will be challenging for our family life, but he is good at balancing many competing demands, and family always comes first for him," said Staudenmaier, a staff attorney at the Washington Legal Clinic for the Homeless. "The fact that he will be a voice for so many people in this county who are frequently ignored makes it hard not to be supportive."

At his election night victory party, Perez cradled his infant son, Rafael, while his older daughter tugged at his pant leg. He talked about the importance of spending time with his children and shaping their paths through life.

"My dad died when I was a kid, so I'm mindful of the fact I grew up in a single-parent household," he said. "But my parents taught me there is no higher service than public service, so running for the County Council seemed like the right thing to do because I'd be making a difference in the lives of others."

Thomas Perez, with wife Ann Marie Staudenmaier and their children -- Rafael, Amalia and Susana -- at their home in Takoma Park, had the support of a multicultural coalition in his run for the County Council.