Organizers expect a "Philly is Baltimore" protest to draw at least 1,000 people to City Hall on Thursday.
The goal, said Deandra Jefferson, a Temple University student and leader of the Philadelphia Coalition for Racial, Economic, and Legal (REAL) Justice, is to support protesters in Baltimore and speak out against police violence.
"Under the right conditions, Philadelphia could be a Baltimore," Jefferson said. "It's something we need to talk about. It's not just a Baltimore issue. It's a nationwide issue."
The rally, set for 4:30 p.m. at 15th and Market Streets, asks Philadelphians to "stand with the people of Baltimore who are rising up against racist police brutality and the murder of Freddie Gray," according to a statement from REAL Justice.
Baltimore erupted in rioting Monday after the funeral for Gray, a 25-year-old African American man who died after being in police custody.
On the coalition's Facebook page, 1,000 people said they would attend the rally. "Bring signs, drums and your voices," says an advisory.
The protest seeks to connect similar issues in both cities, including unemployment, low wages, and incarceration among minorities, and also what the group called "police terror and structural racism."
A focus will be the death of Brandon Tate-Brown, a 26-year-old African American motorist who was shot by Philadelphia police after being pulled over in Frankford in December. Police said Tate-Brown was shot as he reached for a gun in the car.
In March, District Attorney Seth Williams said Tate-Brown's death was a tragedy but not a crime, and the officers involved would face no charges.
Two officers told investigators that after stopping the car, one spotted the butt of a handgun between the console and driver's seat. They ordered Tate-Brown out of the car and tried to arrest him.
Tate-Brown fought with the officers, and was shot when he lunged into the car to reach for the gun, Williams said. Witnesses, video footage, physical evidence, and DNA tests supported the officers' account, he said.
Tate-Brown's mother filed a lawsuit Tuesday seeking to have the evidence in the case made public, and to force city police to put in place a series of reforms.
The REAL Justice coalition consists of about 800 people among 30 organizations, and was formed in response to the high-profile police killings of Michael Brown in Ferguson, Mo., and Eric Garner in New York City.