The mass gathering has been arranged jointly by public-sector staff associations and trade unions to discuss how budget cuts and a pay freeze will affect services and staff morale.
Politicians have been invited to attend and it is expected that there will be strong support from across the spectrum of States employees.
It is the first time that all groups representing States workers have organised a meeting together. Charitable organisations and community groups dependent on States grants have also been asked to attend to say how cuts are likely to impact upon them.
Unite union representative Nick Corbel said that he had received overwhelming support since news of the meeting was made public last week.
