O'Neil's maiden name was Dunham. She was educated in Pennsylvania public schools in the United States and published short stories in American popular magazines from 1913 to 1934 with her peak output being 1918 and 1919. A story, 'Pennsylvania' also appeared in Stockman Stories (1913) and was originally published in the National Stockman and Farmer, a Pittsburgh publication. O'Neil lived in Brisbane, Queensland, during the early 1920's before moving to Killarney on the Darling Downs. She contributed poetry, fiction and magazine articles to Queensland and other Australian newspapers and journals including The Bulletin. H. A. Kellow's Queensland Poets (1930): 246 comments: 'The courageous poetry of Lydia O'Neil, devotee of the creed of Kipling and Noyes, braves its discipleship in Dinkum Aussie (slang for 'genuine Australian') and leaves no observance out. For Miss O'Neil loves to write of soldiers and sailors and other of the King's men, of bonny jackaroos, of lean brown men nursed in a lean brown land - Australians all;...She is a typical extraverted sensationist, viewing Port o' Spain, Hong Kong, Alaska, Norway, Bokhara, or Ning-Po-Fu! The romantic glamour of these places lies primarily in herself. And so everywhere she puts a brave face on the outside world; there is the will to make the beautiful and to see all things at their best, as that best is conditioned by the poet.' (Source: J.H. Hornibrook's Bibliography of Queensland Verse With Biographical Notes (1953): 58)
