Gwen McCarthy was born Gwendolen Helen Ure in Norwood in 1901. She was educated at Methodist Ladies College (now Annesley College) and studied law at Adelaide University, where, in 1923, she was awarded the prestigious Stow prize and medal, styled Stow Scholar because she won three prizes in her annual examinations that year. Gwendolen Ure was the first female Stow Scholar.

She joined the Lyceum Club in Adelaide in 1923 and was president 1967-1969. She married James McCarthy in 1927 and they set up a law practice in Kadina. Here she was involved in the Girl Guides. On her husband's death McCarthy returned to Adelaide and joined the firm of Thompson, Cleland, Holland and McCarthy.

Sources used to compile this entry: Address by Aileen Bond and Constance McCarthy [sound recording], c. 1987, SRG 438/29/36; State Library of South Australia, Mortlock Library of South Australiana.