Gago was born in Mooroopna, Victoria, and completed her secondary education at Shepparton High School.
After high school, Gago studied at Phillip Institute of Technology and the Austin Hospital where she graduated as a registered nurse, later completing a Bachelor of Science (Honours) at Monash University, majoring in psychology.
[citation needed] In 1987, Gago and her husband Peter moved to South Australia, where she worked as a nurse at Salisbury Private Hospital for two years.
[1] As a member of the ANF, Gago was part of many campaigns to improve patient care, access to health services, wages and conditions for workers.
After the resignation from Cabinet of Bernard Finnigan, Gago became acting Leader of the Government in the Legislative Council.