As Jealous prepares to step down five years later, he's credited with boosting the organization's fundraising and helping to stabilize it.
Jealous plans to further discuss his decision to step down as president and CEO of the nation's largest civil rights organization Monday, a day after it was first announced. His departure is effective Dec. 31.
In a written statement, the 40-year-old Jealous said he plans to teach at a university and wants to spend time with his young family.
"The NAACP has always been the largest civil rights organization in the streets, and today it is also the largest civil rights organization online, on mobile and at the ballot box too," Jealous said. "I am proud to leave the association financially sound, sustainable, focused, and more powerful than ever."
The news was met with a mixture of sadness and appreciation from other civil rights leaders who admired how he helped the organization. Jealous was the group's youngest-ever leader when he was hired as its president at age 35 in 2008.
The Baltimore-based organization said its rosters of online activists and donors have grown tremendously during his five-year tenure.
In the year before Jealous arrived, the NAACP cut its national staff by a third because of what a spokesman described at the time as several years of falling fundraising revenues. Also that year, former NAACP President Bruce Gordon abruptly resigned after clashes with the group's 64-member board.
The group said its donors have increased from 16,000 people giving each year to more than 132,000 under the leadership of Jealous.
During Jealous's tenure, the NAACP also has embraced gay rights in a historic vote to endorse same-sex marriage in May 2012. "Civil marriage is a civil right and a matter of civil law," the group said, citing the 14th Amendment's equal protection clause.
Jealous told The Associated Press recently that a broader coalition is needed to fight the civil rights battles of the 21st century.
"Last century we needed lawyers; this century we need big, broad coalitions," he said. "When extremists decide to attack all our communities, they must hope that there will be infighting. But we have stood all for one and one for all. That is how we will win."
An NAACP spokesman said Jealous was not available for an interview until a formal announcement Monday.
Jealous told USA Today that he also plans to start a political action committee to raise money to elect diverse progressive candidates to public office, though not necessarily only Democrats. During President Barack Obama's first campaign, Jealous said he teamed with others to create a fundraising group that raised $10 million to help elect the first black president.
The newspaper said he was in the first year of a three-year contract.
The Rev. Joseph Lowery, a civil rights leader and former president of the Southern Christian Leadership Conference, said Jealous brought an intellectual quality and a level of integrity that won respect.
"I'm sorry to see him resign, although I understand he has other plans. But, I think he was just getting into his stride," Lowery said Sunday evening. "I think he brought a luster to the office that was quiet and dignified and effective, and I wish him well in his new work."
The Rev. Al Sharpton said he felt "mixed emotions" about Jealous' announcement, which included sadness because Jealous had led the organization so well.
"Not only was he able to revive the NAACP and raise its budget to higher heights, he joined us in the streets in real civil rights activity on the ground," Sharpton said in a written statement. "From the 'suites to the streets,' he will be missed as head of the NAACP, but I am sure he will not leave us in his contribution to the struggle."
Jealous began his career as a community organizer in Harlem with the NAACP Legal Defense Fund. He was suspended from Columbia University in New York City after organizing student protests and went on to work as a reporter for the Jackson Advocate newspaper in Mississippi.
Jealous has led the NAACP to advocate against "stop-and-frisk" police tactics and stand-your-ground laws following the death of Florida teenager Trayvon Martin. He has also fought to abolish the death penalty at the state level, including in Maryland.
NAACP Chairman Roslyn Brock accepted Jealous' resignation in the past week. She thanked Jealous for his service in a statement.
"Under his leadership, the NAACP has built a highly competent staff that will carry our mission forward and meet the civil rights challenges of the 21st century," she said. "Our board, staff and volunteer leaders throughout the country deeply appreciate his sacrifice and will continue to implement our game-changing goals for the next half century."
Associated Press writer Phillip Lucas in Atlanta contributed to this report.
Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.