Chief executives body Acevo has urged third sector organisations to get involved straight away with helping to define the government's big society agenda.
Stephen Bubb, chief executive of the organisation, welcomed announcements yesterday by David Cameron and Nick Clegg, including the confirmation that they intend to establish a big society bank and set up a national citizen service to encourage young people to volunteer.
Bubb said the moves were an early indication that the government was serious about the voluntary sector.
"To have the Prime Minister and the Deputy Prime Minister talking about our agenda very early on is a big signal that we are being taken seriously," he said.
But he warned that the sector must be proactive in engaging government in order to flesh out the details of the plans.
"How we define the big society is not just up to government," he said. "The sector has to be involved. We have said that we will work in partnership with them and that means we are involved in defining how it works."
Dame Elisabeth Hoodless, executive director of volunteering organisation CSV, warned that plans to hold a big society day should not duplicate other initiatives such as CSV's Make a Difference Day, which encourages people to volunteer.
She welcomed the concept of a national citizen service but said it was "important that young people should be able to tackle real community problems rather than simply doing something for a week and then going off elsewhere".
She called for a programme allowing 18-year-olds to give a year of service between school and university or before they started their careers.
Justin Davis Smith, chief executive of Volunteering England, said the government would need to learn from the knowledge of the volunteering movement, as well as developing new ways of working, to achieve its vision.
"The proposals for a big society day, for community involvement by civil servants and for the voluntary national citizen service are all welcome progress," he added. "We look forward to discussing the next steps with ministers."
Peter Holbrook, chief executive of the Social Enterprise Coalition, welcomed the commitment to establishing a big society bank and for social enterprises to play a larger role in public service delivery. He said his organisation was ready to work with the government and would also work hard to influence it "more broadly on how social enterprise can play a stronger role in the wider economy".
"This is a step in the right direction, but as it is early stages, there is still much we don't know," he said. "We await greater clarity as to whether the Liberal Democrat proposal for a mutuals, cooperatives and social enterprise bill, with a minster given responsibility for mutuals, will come to fruition."