The RUC’s name officially changed at midnight last night to the Police Service of Northern Ireland (PSNI).
New recruits to force begin training today.
Sinn Féin is the only main political party so far not to have given the force its full support.
The party is refusing to take up its positions on the Police Board which begins its business on Wednesday.
Sinn Fein has refused to take its two seats on the board which will hold its inaugural meeting in Belfast on Wednesday.
The board, which is chaired by Professor Des Rea, is made up of nine non-political members and 10 drawn from the Stormont Assembly.
Ulster Unionists have four seats on the board, the SDLP and DUP have three each.
The SDLP's participation on the board was seen as crucial to the ability of the new police service to achieve its goal of attracting more Catholic recruits and making the service more representative of Northern Ireland.
It is the first nationalist party in the history of Northern Ireland to urge its supporters to join and support the police.
Sinn Fein is opposed to the new service because it argues the police reforms do not go far enough.
They would like plastic bullets to be banned and more police accountability to the board.
PA