Ministerialists and Oppositionists (Western Australia) were political groupings that were in force in the Western Australian parliament in the elections of the early twentieth century.
The turbulent and unresolved alignments in Western Australian politics following the John Forrest era did not settle until after the first world war.
The Ministerialist grouping in 1911 evolved into the Western Australian Liberal Party (1911–17) interestingly under the guidance of John Forrest.
The Ministerialist term was still in use in the 1920s. and in the 1940s.
In other states of Australia the term had been used prior to federation.