Joseph Gordon Coates served as the 21st prime minister of New Zealand from 1925 to 1928. He was the third successive Reform prime minister since 1912.

The Reform Party, formally the New Zealand Political Reform League, was New Zealand's second major political party, having been founded as a conservative response to the original Liberal Party. It was in government between 1912 and 1928, and later formed a coalition with the United Party, and then merged with United to form the modern National Party.