Some say the number of nonprofits isn't the issue; it's that the sector could work more efficiently if some organizations teamed up. "It's a nuanced conversation," says Eric Weinheimer, CEO of Chicago-based Forefront, which represents public agencies, nonprofits, funders and advisers. "It's not about too many—it's about ensuring they can focus on their mission and serve communities." He's more likely to discourage than encourage a nonprofit startup. "Nine times out of 10, there's an organization aligned with your interest and services," he says. "You need to talk to those."

Earlier this spring, Forefront launched Mission Sustainability, a program that offers counsel and resources to nonprofits wishing to merge or otherwise collaborate. In eight weeks, it received 80 phone calls from interested organizations. The volume "confirms what we knew was out there," Weinheimer says.