She is particularly known for her work on language contact in Australia, having described and documented what is now known as Light Warlpiri.
She worked as a teacher in Indigenous schools in Australia's Northern Territory in the 1990s.
O'Shannessy worked as a bilingual education teacher in the Northern Territory in 1996.
She received her PhD from the University of Sydney and the Max Planck Institute for Psycholinguistics in 2006.
[6][7] She has received funding for her work on Light Warlpiri and language acquisition in the Northern Territories from the National Science Foundation (USA) and through the Australian Research Council's Future Fellows programme.