Prichard was a founding member of the Communist Party of Australia in 1921 and remained a member for the rest of her life. She worked to organise unemployed workers and founded left-wing women's groups, and during the 1930s she campaigned in support of the Spanish Republic and other left-wing causes. Although she had frequent arguments with other Communist writers such as Frank Hardy and Judah Waten over the correct application of the doctrine of socialist realism to Australian fiction, she remained supportive of the Soviet Union and its cultural policies when many other intellectuals, such as Eric Lambert and Stephen Murray-Smith, left the party during the 1950s. Her public position as both a communist and a female writer saw her harassed by West Australian police and the federal government throughout her life. The official surveillance files which were opened on Prichard in 1919 were not closed until her death in 1969.