Unlike past debates, which were dominated by how the candidates favor expanding health insurance coverage to millions of Americans, Democrats touched on the issue only briefly before moving onto longer exchanges on abortion access, climate change and foreign policy.
Here are some highlights from the stage in Atlanta, where 10 of the candidates seeking the Democratic nomination to take on Republican President Donald Trump in November 2020 are debating:
'NAME YOUR FAVORITE WOMAN PRESIDENT'
The night featured an extended conversation about gender, experience and who has the most broad-based appeal.
Pete Buttigieg, whose only political experience is as mayor of South Bend, Indiana, sought to turn his lack of time in Washington into an advantage.
"I know that from the perspective of Washington, what goes on in my city might look small, but frankly where we live, the infighting on Capitol Hill is what looks small," he said.
U.S. Senator Amy Klobuchar, who previously said a woman with Buttigieg's experience would not have made it to the debate stage, reiterated her argument that women are held to a higher standard.
"Otherwise, we could play a game called 'Name your favorite woman president,' which we can’t do," she said to applause.
The United States has never sent a woman to the White House.
Klobuchar then used the moment to take aim at former Vice President Joe Biden's claim that he alone can win in swing states, pointing out that she has carried Republican districts in her home state of Minnesota.
In response, Biden touted his record of passing bipartisan legislation and his long experience in Washington.
"There’s no time for on-the-job training," he said. "I spent more time in the Situation Room, more time abroad, than anyone up here."
BLACK VOTERS
Buttigieg also was pressed on his failure to gain traction among black voters, a crucial bloc in the Democratic nominating contests.
Buttigieg, who has risen in polls in the mostly white early-voting state of Iowa, has been criticized by the black community in South Bend, where he fired the city's first black police chief in 2012 and faced protesters earlier this year after a police officer shot a black man.
U.S. Senator Kamala Harris, who is black, said she believed the Democratic nominee should have experience representing all people and should understand that black voters should not only be courted at election time.
"Democrats have taken for granted the constituency that has been the backbone of the Democratic Party," Harris said. "They show up when it's close to election time in a black church and want to get the vote."
Buttigieg acknowledged he faces a "challenge" in introducing himself to many black voters, before pivoting to his own experience as a gay man.
"I do not have the experience of ever being discriminated against because of the color of my skin," Buttigieg said. "I do have the experience of feeling like a stranger in my own country, turning on the news and seeing my own rights coming up for debate."
Biden, who leads the Democratic field in support from black voters in opinion polls, later said the reason he was chosen as former Democratic President Barack Obama's vice president "was because of my relationship, my long-standing relationship with the black community."
CLINTON'S LEGACY
U.S. Representative Tulsi Gabbard doubled down when asked about her clash with the party's 2016 presidential nominee, Hillary Clinton, last month.
Gabbard, an Iraq war veteran who has centered her campaign on opposition to overseas military intervention, said the Democratic Party "continues to be influenced by the foreign policy establishment in Washington, represented by Hillary Clinton and others' foreign policy, by the military-industrial complex and other greedy corporate interests."
Asked to respond, Harris defended Clinton. Gabbard criticized former Democratic President Barack Obama's administration on Fox News, said Harris, who linked Gabbard to former Trump adviser Steve Bannon and brought up her support for Syrian leader Bashar al-Assad.
Harris said she was the candidate who could rebuild the coalition of voters that elected Obama twice.
Gabbard shot back at what she called Harris' "lies and smears and innuendoes," and said Harris would continue U.S. foreign policy failures of the past.
Later, Buttigieg criticized Gabbard's decision to meet with Assad, saying he "would not have sat down with a murderous dictator like that."
FREELOADING BILLIONAIRES
U.S. Senator Elizabeth Warren answered a question about how she would unify a divided country by reintroducing her proposed 2% tax on wealth beyond $50 million, with an additional 4% tax on wealth beyond $1 billion.
"I'm tired of freeloading billionaires," said Warren, whose proposal has prompted contentious responses from several prominent billionaires in recent weeks.
"Regardless of party affiliation, people understand across this country, our government is working better and better for the billionaires, for the rich, for the well connected, and worse and worse for everyone else," Warren said, adding that the tax would pay for free public college and universal childcare, while also canceling most student loan debt.
U.S. Senator Cory Booker was asked whether he agreed with Warren's proposal, leading to the first policy disagreement of the night.Booker said he did not support Warren's wealth tax but if elected, he would pursue "fair and just taxation where millionaires and billionaires pay their fair share." He agreed with Warren that "we need to raise the estate tax, we need to tax capital gains as ordinary income."