One of the central challenges for the social entrepreneurs we’ve been covering in our Business of Good series is striking the right balance between impact and profit. Well, now there’s a new legal designation in Massachusetts designed for those who think both goals must be taken seriously.

Earlier this week, Governor Deval Patrick signed into law an economic development bill that included a provision creating a new type of corporation in the Commonwealth: the benefit corporation.

This new category provides social entrepreneurs in Massachusetts with a legal framework that fits the desire to balance profit and social mission. As the nonprofit B Lab, an advocate for the legislation, explains in a release:

Benefit corporations are a new kind of corporation legally required to: 1) have a corporate purpose to create a material positive impact on society and the environment; 2) expand fiduciary duty to require consideration of the interests of workers, community and the environment; and 3) publicly report annually on its overall social and environmental performance using a comprehensive, credible, independent, and transparent third party standard.

That second one is quite important. Whereas the board of directors in a typical corporation is charged with pursuing the interests of the corporation first and foremost, benefit corporations are allowed room to consider that interest in the context of the other interests named above.

So what company will be Massachusetts’ first benefit corporation? The law takes effect in January, but there’s reason to think that some demand exists already for the designation.

B Lab, the nonprofit that helped advocate for the law, certifies companies socially conscious companies (and serves as a third party standard in states that allow benefit corporations). But even though the benefit corporation designation hasn’t existed in Massachusetts, B Lab has already certified 18 “B Corps” in the state.

“This is a common need. There’s a wide group of businesses who are demanding this,” said Katie Kerr of B Lab. So who will be the first business in the state to incorporate as a benefit corporation?

“Startups love it,” Kerr told me. “It’s easier for them because they haven’t incorporated yet.”

Kerr said that while many of the businesses that come to B Lab seeking certification and that choose to incorporate as benefit corporations have a direct social mission at the core of their business, many are just looking to be better employers and stewards of the environment.

In other words, your main product doesn’t need to be mosquito nets or water filtration systems to qualify. Lots of companies just take it as an opportunity to demonstrate their commitment to their employees and their community.

The B Lab credits Senator Brian Joyce and the American Sustainable Business Council as key advocates that helped push through the legislation in Massachusetts.

With the law passed, the only question now is what business will be first.