New ballot boxes will be available in Suffolk County jails this fall to kick off an expansion of voting opportunities for thousands of incarcerated people across the state beginning with primaries in September.

Under Massachusetts law, people who are convicted of felonies cannot vote while they are in prison. But that doesn’t apply to the many people in jails who are waiting for their trials, or have been convicted of misdemeanors.

“It’s a de-facto disenfranchisement because though they have the right, many people don’t know they have the right and the infrastructure is not in place,” said Pastor Franklin Hobbs, the founder and director of Healing Our Land, a nonprofit focused on addressing the needs of people returning from incarceration.

A group of nonprofits, backed by the city of Boston and Harvard University, are setting up the new collaborative effort that will provide both voting opportunities and information to incarcerated people about voting rights and the importance of civic engagement, organizers said.

“The idea is to expand voter access behind the wall,” said DeAnza Cook, a Healing Our Land board member. Part of that, she said will be making it easier to cast a ballot, by “providing official locked boxes, and kind of deputized mobile boxes we can carry out through the units so that folks that are immobile or unable to go to the official lock box to cast their ballot” can vote.

But a second factor will be educating incarcerated people about their rights. Cook and Hobbs said they will be bringing volunteers into the detention centers — particularly volunteers who have been previously incarcerated — for trainings and conversations about voting and civic engagement.

Mayor Michelle Wu celebrated the Ballots Behind Bars Initiative in a press release Thursday.

“Ensuring that every eligible voter has access to opportunity and resources is critical to ensuring that Boston is a city for everyone,” Wu wrote in a statement.

The group is also “going into the units or the individual facilities where folks live, and we’re hosting absentee ballot application and voter registration workshops,” Cook said.

The effort builds on the VOTES Act, the 2022 state law requiring all correctional facilities to provide voting information and ballot access to incarcerated people who retained their voting rights. It is being supported with a $350,000 grant from Harvard’s “legacy of slavery” grant program, as well as smaller grants from the city of Boston, Cook said.

As the project begins in the next few weeks, organizers are setting a fairly modest bar for participation: about 200 people in the South Bay House of Correction and the Nashua Street Jail. Across those two facilities, about 850 people are eligible to vote, according to February data from the sheriff’s office. Hobbs and Cook said that in prior years’ efforts to help incarcerated people vote at the same locations, they have collected between 50 and 75 ballots.

Organizers hope the project could ultimately open the door for thousands of incarcerated people across the state to cast ballots.

Hobbs said “this is the model that we want to really develop, make robust and then have be the pilot … to replicate throughout the rest of the commonwealth.”

The National Institute of Corrections estimated in 2020 that there were about 9,400 people incarcerated in county jails across the state; advocates say most of those people would still be eligible to vote.

Suffolk County Sheriff Steve Tompkins told GBH News that the new initiative builds on programs he has been implementing for years. He says Suffolk County has had ballot drop boxes inside the detention facilities, but he looks forward to the city and others take on the work of making it easier for incarcerated residents to vote.

“Just because you’re incarcerated, I don’t think that that should preclude you from being a part of the democratic process,” Tompkins said. “You should be able to vote. I think that is very important.”

And he says it is critical to help incarcerated people learn about the importance of voting and civic participation because they often come from communities and families that have largely given up hope that their vote matters.

“We think that it’s crucially important to at least put that information in front of people that are here with us,” Tompkins said, “and I think that we’re negligent if we don’t.”