The Constitution of New South Wales gives the Governor of New South Wales the authority to appoint Ministers as well as Judges, Commissioners, Justices of the Peace and other necessary officers. In practice, the Governor asks the leader of the party or parties able to command a majority in the Legislative Assembly (Lower House) if they can form a government. If assured that they can, the Governor appoints that person as Premier.

The Premier will then nominate the remainder of the new ministers and the Governor will appoint them. In effect, the Premier selects the Ministry and the portfolios Ministers will hold. One qualification to this is that in Labor Governments the selection of people to become Ministers is made by the Parliamentary Labor Party (”in Caucus”) and the Premier allocates the actual portfolios (positions).

Various events may lead to appointment of a new Ministry. The most obvious is a General Election. Once an election has taken place and the outcome is clear, the Governor invites the majority leader in the new Legislative Assembly to form a government. Even if the previous government is returned to office, the Premier will normally submit his resignation as Premier, but then will be commissioned by the Governor to form a new government. If the previous government has lost the election, the Governor will invite the leader of the party or parties now commanding a majority in the Lower House to form a government. The new Premier will then recommend the new Ministers for appointment by the Governor.

A change of government can occur without a General Election. If a government is defeated on the floor of the Legislative Assembly on a significant issue and can no longer command the confidence of the House they are expected to resign. The Governor will then attempt to appoint a new Premier with command of the House. If stable government becomes impossible, the Governor can call a new General Election.

Changes to the Ministry often take place without changes of government, through resignations, retirement or death. Alternatively, a Premier may decide to reconstruct the Ministry, reallocating some portfolios, appointing new Ministers or removing some existing ones. The procedure is much the same, with the recommendation submitted to the Governor who then makes the appointments.

On appointment, Ministers are required to take oaths of allegiance to the Queen and to affirm that they will, to the best of their judgement “... freely give my counsel and advice to the Governor or Officer administering the Government of New South Wales for the time being for the good management of the public affairs of New South Wales ...” They also affirm that they will keep Cabinet confidentiality (ie not publically discuss what happens in Cabinet).