Organizers for the Boston event have invited "libertarians, conservatives, traditionalists, classical liberals, (Donald) Trump supporters or anyone else who enjoys their right to free speech," according to a group calling itself the Boston Free Speech Coalition.
Boston will have counterprotesters, too -- organized by a coalition of mostly left-leaning groups and activists such as the Black Lives Matter movement.
After the city granted a rally permit earlier this week, Boston Mayor Marty Walsh issued a statement: "Make no mistake: we do not welcome any hate groups to Boston and we reject their message."
"We have made it clear that we will not tolerate incitements to violence or any threatening behavior."
Here's what to expect in Boston:
Who's behind the rally?
"We are a coalition of libertarians, progressives, conservatives, and independents and we welcome all individuals and organizations from any political affiliations that are willing to peaceably engage in open dialogue about the threats to, and importance of, free speech and civil liberties," says the Facebook page linked to the event.
Some of the same groups organized a similar event on the Common in May, where there were two arrests.
One organizer, John Medlar, a student at Fitchburg State University, told CNN affiliate WCVB
that his group is libertarian and opposes bigotry and the Ku Klux Klan.
Medlar also told CNN affiliate WBZ
, "Contrary to a lot of the rumors out there, the purpose of the rally is to denounce the kind of political violence that we have seen -- a sort of rising tide throughout the country, and particularly most recently in Charlottesville."
The Anti-Defamation League
said the Boston rally, as planned, is not a white supremacist event.
"It has been organized under the auspices of the alt lite, which embraces civic nationalism, rather than the alt right, which advocates white nationalism," the ADL said in a blog post
"The alt lite, sometimes referred to as the New Right, is a loosely-connected movement whose adherents generally shun white supremacist thinking, but who are in step with the alt right in their hatred of feminists and immigrants, among others. Many within the alt lite sphere are virulently anti-Muslim; the group abhors everyone on 'the left' and traffics in conspiracy theories."
When and where will the rally take place?
The rally is set to begin at noon on the historic Boston Common, and police said they anticipate large crowds.
Counterprotesters are expected to gather at 10 a.m. at the Reggie Lewis Track and Athletic Center in Roxbury.
Who will speak?
Some speakers have dropped out, while others were uninvited after Charlottesville. But rally organizers said on social media that Kyle Chapman, Joe Biggs, US Senate candidate Shiva Ayyadurai and congressional candidate Samson Racioppi have been confirmed.
Chapman and Biggs are probably the most controversial.
Chapman is well-known in right-wing circles for arming himself with a stick and confronting anti-fascist demonstrators in Berkeley, California, according to the ADL. Known by the nickname Based Stickman or the Alt Knight, he has urged members of his group to battle left-wing activists, the ADL said.
Biggs, a former contributor to Alex Jones' InfoWars
, is chief operations officer at the online outlet Rogue Right Media.
Who are the counterprotesters?
The counterdemonstration has been organized by an array of groups, including the Coalition to Mobilize and Organize Boston against Trump, the Act Now to Stop War & End Racism Coalition, Boston Democratic Socialists of America and Black Lives Matter, according to a Facebook page for the event.
"As we have seen with the events in Charlottesville and around the country, white nationalists are emboldened by the current political administration and growing police state," organizers wrote on Facebook.
"Rallies and marches organized by white supremacists are more prevalent than in recent years, and -- as always -- it is the most marginalized who are left vulnerable."
Monica Cannon, an organizer with the group Violence in Boston, said activists who participated in last week's Charlottesville event will attend. She said tens of thousands of counterprotesters are expected.
The ADL said in its blog, "Given the heightened tensions in the wake of Charlottesville, the Boston event could certainly see clashes between attendees and counter-protesters, who appear prepared to come out in force."
How will the city and police respond?
Walsh, the mayor, and Boston Police Commissioner Williams Evans said the city is prepared should violence break out.
More than 500 police officers -- including some undercover and others with cameras -- will be there.
Backpacks will be searched and weapons, and objects that can be used as weapons -- including glass containers and flag poles -- will be banned.
"If anything gets out of hand, we will shut it down," Walsh told reporters Friday.
Walsh said the city had no choice but to issue a rally permit.
"The courts have made it abundantly clear they have a right to gather no matter how repugnant their views are," he said.
He added, "This so-called free speech rally -- some of the people speaking have said some very hurtful things about the Jewish community, about the African-American community, about a whole bunch of other communities. I don't want them here."
Evans said the demonstrators and counterprotesters would be kept apart on the Commons.
"Unfortunately, I think there are going to be a few troublemakers there," he said.