The crowd-funding community is split over a proposal that would let businesses sell equity stakes through the social-networking function.

Some operators of crowd-funding platforms are eager for the new opportunity. Others say the change runs counter to their underlying mission.

Crowd-funding platforms, which first appeared about a decade ago, initially were used by artists, filmmakers and the like as a way to raise cash for discrete projects. Early contributors often were friends or fans.

But since credit markets tightened after the financial crisis, small businesses discovered the platforms as a way to get funding, generally through small-dollar pledges from a big collection of online contributors.

Cupcake Suite Cupcakery, a New York start-up wholesale bakery founded by three cookbook authors, last fall raised almost $9,000 in part through a crowd-funding platform to help offset the cost for a planned new location. Any contributor who provided at least $25 got a half-dozen whoopie pies.

That form of crowd funding is fairly low risk because there's no expectation of financial profit for those who contribute. Business owners are limited to offering only token gifts, such as T-shirts or mugs.

But Sally Outlaw, the co-founder of Jupiter, Fla., crowd-funding platform Peerbackers LLC, says such rewards can only go so far. "If people who don't know you back you, obviously they're more motivated by some sort of return," she says.

Like Ms. Outlaw, Slava Rubin, the co-founder and chief executive of crowd-funding platform IndieGoGo Inc., supports the idea of expanding crowd funding to sales of equity stakes. He says his site has helped users secure funds for roughly 45,000 projects since 2008, taking a 4% cut on contributions.

Brian Meece, co-founder and CEO of RocketHub Inc., is less enthusiastic. Crowd funding is "really more about the emotions and less about the transactions," he says. He cites a fundraiser who used the method to raise money and named the new wing of a building after a contributor.

An equity stake in a small company could appeal to investors hoping to get in on "the next Facebook," Mr. Meece says, but most of the campaigns on RocketHub are for the arts.

—Angus Loten and Sarah E. Needleman