How successful were the socialists and communists in exploiting the unrest caused by the Depression?

Fascists, Socialists, and Communists all had a boom during the depression, as each claimed to be the 'fix' for the Depression. Memberships soared for all groups. Infact, the Great Depression was a major factor in Adolf Hitler coming to power and some would argue that he would not of reached power in Germany if it had not occurred.