As Massachusetts residents continue to feel the squeeze of the state’s housing crisis, a real estate group is making the case that tweaking a 20-year-old law could help.

The Greater Boston Real Estate Board and Tufts University’s Center for State Policy Analysis partnered to review the state’s Community Preservation Act, and found that more than a third of the cities and towns that have opted into the program are coming up short on their affordable housing commitments.

The CPA, signed into law in 2000, allows communities to add a surcharge on top of their local property taxes, and requires that participating communities devote at least 10% of the money raised to affordable housing.

But according to a report released by the two organizations Tuesday, of the 195 cities and towns participating in the CPA, 70 have not hit that 10% spending mark since joining the program, though they may have set aside money for future housing investments.

Communities that adopt the CPA can also use the money for open space, recreation and historic preservation, as well as affordable housing.

Those priorities can sometimes be in conflict with one another — choosing to build housing on a property means it can't become conservation land, and vice versa — and it's up to the communities to decide how to spend their money.

“All of these areas, they're all important, they're all part of what makes the kind of umbrella of the CPA work,” said report author Evan Horowitz, the executive director of the Center for State Policy Analysis. “But you know, it's been 20 years and housing is obviously the thing everyone's talking about. It's the crisis that the state's facing, one of the biggest crises that the state is facing.”

The report said CPA investments in housing are "especially limited" in Massachusetts suburbs, while urban areas devote more than half of their CPA spending to housing and rural areas more than 40%.

The report recommends several steps the state could pursue to "rebalance" the CPA to consider the state's challenges of limited housing supply and soaring costs. Those measures include enforcing the 10% requirement, offering additional state money to communities that commit at least 20% of their CPA money to affordable housing, and creating a dedicated team within the state government to help smaller towns handle tasks like bidding and project management.

Greg Vasil, the CEO of the Greater Boston Real Estate Board, said he hopes the report can spur a broader discussion about the CPA and whether there's a way to strengthen its potential as its housing production strategy.

"Is there a way to create more incentives for communities that really want to build?" he said. "Because I think it is a real viable tool for the creation of even more housing for those communities that want to use it in that way."