The plan, which is called Partnership in Public Services, was launched by four ministers: third sector minister Ed Miliband, paymaster general Dawn Primarolo, care services minister Ivan Lewis and Jim Murphy from the Department for Work and Pensions. It lists four areas for change: accountability, commissioning, procurement and learning from the third sector.
On commissioning, the Government proposes to train up to 2,000 of the "most significant" commissioners in the skills and knowledge necessary to involve more third sector organisations in the delivery of public services.
"Commissioners need to understand far better the needs of the sector and what the sector can contribute," said third sector minister Ed Miliband.
"There is no alternative to this commissioner-by-commissioner approach."
According to Miliband, five government departments have already signed up to eight new commissioning principles set out in the plan.
These include consulting potential provider organisations in advance of commissioning new services and seeking to ensure long-term contracts and risk-sharing wherever appropriate.
The Government has pledged to make procurement processes fairer and more proportionate by drawing up a set of standard contracts for public bodies contracting services from the voluntary sector.
It is also going to look into how subcontracting between the voluntary and private sectors and between large and small charities can be improved.
A quality standard for subcontracting could be introduced.
An innovation exchange website will be developed for those charities that want to help spread best practice from the voluntary to the public sector.
"You'll be relieved to know it won't be run by government," said Miliband. "It'll be run at arm's length." The Office of the Third Sector will act as a broker of dialogue and exchange between the two sectors.
The action plan sets out several ways in which the third sector can help communities have a greater say in how local services are run.
Initiatives include the creation of a user-led organisation in every area by 2010 and the transfer of successful methods of encouraging citizen involvement from local government to national government departments.
Lewis said: "We have to focus on outcomes for those who use services."