About 300 workers and supporters of kohunga reo have arrived in Wellington to support their claim which starts before the Waitangi Tribunal on Monday.
They were welcomed with a powhiri at Wellington's Pipitea Marae on Sunday afternoon.
The supporters have come from around New Zealand.
They object to Government policy which they say treats the Maori language centres for preschoolers under rules that apply to early childhood education generally, and believe it will undermine the movement.
Supporters say they have exhausted efforts to persuade the Crown that kohanga reo are not just early childhood education centres, but whanau-based organisations which the Government is obliged to support under the principle of partnership between Crown and Maori.
The hearing is expected to take two weeks.