Politicians, trade union officials and campaign groups are gathering to voice their opposition to the Government's planned multi-billion pound spending cuts.
The coalition Government outlined its deficit reduction measures in last month's Comprehensive Spending Review (CSR). It is thought that the plans could cost about 490,000 public sector jobs over the next four years.
MPs, trade unionists, including Len McCluskey, newly-elected general secretary of trade union Unite, students and pensioners' groups are among those expected to attend the first Coalition of Resistance Conference in central London.
Prime Minister David Cameron insisted that the expected £81 billion cuts package would be "fair" and support economic growth.
Almost 1,000 delegates have registered for the event to hear speakers and attend workshops aimed at galvanising a "national movement" against cuts to public services, organisers said.
Mr McCluskey will be among those speaking. He said: "We have to build a kind of resistance and take action that makes politicians and in particular the Lib Dems say: 'We may have got this wrong'."
Other trade union leaders speaking at the conference include Bob Crow, general secretary of the RMT, Mark Serwotka, general secretary of the Public and Commercial Services Union, Heather Wakefield of Unison and Jeremy Dear, general secretary of the NUJ.
Veteran politician Tony Benn, Labour MPs John McDonnell and Jeremy Corbyn, film director Ken Loach and singer Billy Bragg are among other figures who will address the conference.
Student activists who took part in this week's protests against the Government's plans for higher tuition fees will also be involved.