U.S. Rep Joseph P. Kennedy III , D-Mass., spoke at Saturday's event.
"We cannot let up for a minute. We need your passion. We need your voices," Kennedy said to the crowd in Faneuil Hall Saturday.
U.S. Sen. Elizabeth Warren, D-Mass., joined Kennedy and said she would fight for a path to citizenship.
The "Power Up for Citizenship" event included other rallies and marches in New Hampshire and Providence, The Boston Herald said.
The campaign hopes to create pressure to force Congress into adopting immigration reform.
The bipartisan group of senators working on immigration reform is expected to released details of the proposal as early as this week, the Herald said.
Despite backlash from many who try to limit immigration, Warren and Kennedy said they are optimistic the measure will pass.
"I'm going to hope that the will of the people will win out here. People want us to get this fixed," Warren said.