The Sewell Ministry was the first responsible government in New Zealand. Unlike previous executives, its members were held accountable to Parliament. This would form the basis for future governments in New Zealand.
The ministry formed in 1856, but lasted only one month, from 18 April to 20 May. From 7 May onwards, Henry Sewell held office as colonial secretary, considered to be the equivalent of a prime minister or premier. Thus, Sewell is regarded as the first prime minister of New Zealand.