A by-election for the seat of Boulder in the Legislative Assembly of Western Australia was held on 4 December 1948.
The Labor Party retained the seat at the election, with Charlie Oliver winning 78.9 percent of the first-preference vote.
[2] Oliver was re-elected unopposed at the 1950 state election, but resigned his seat the following year to take up a position in the New South Wales union movement.
[3] One of his opponents for Labor preselection was John Teahan, who later won election to the Legislative Council in 1954.
[4] Billy Snedden, the unsuccessful Liberal candidate, eventually moved to Victoria and was elected to the House of Representatives.