Matthew Scott, director of the coalition, whose members include local infrastructure body Navca, volunteering charity BTCV and Community Matters, which represents community organisations, said there were widespread fears that big society was a codeword for "big cuts".
He said unless something was done to address these concerns the project might be doomed before it had begun.
"Community action is not a soundbite; it grows up over years of hard work, and this needs protecting and investing in," said Scott. "Now is the time to get real about what it takes to build society from the grass roots."
He praised the Conservatives' support of a wider approach to civil society but said the new coalition government needed to listen to small community groups about what worked if it wanted to make a difference.
Scott, whose organisation has a membership of 25 umbrella organisations, said coalitions were "an inclusive way to achieve common goals and better outcomes" and hoped the new government adopted this approach to the voluntary sector.
"The Community Sector Coalition welcomes an election outcome that encourages collaborative working," he said.
"We hope that the new government will improve on the ‘pick-and-mix' approach to third sector policy in the manifestos.
"Without a clear policy for investment in supporting communities and neighbourhood groups, there is a likelihood that local activity will decline."