Maggio has worked and volunteered for AIDS and gay organizations in Chicago since the 1980s. She was born in New York and married a man in her 20s, before she came out as a lesbian. When she came to Chicago in 1985 she became involved in the early formation of Chicago House, a home for people with HIV and AIDS. She was the first development director for AIDS Foundation of Chicago and part of developing the first major AIDS civic event, The Show of Concern, in 1987. She was later acting executive director of AFC. She has also been executive director of STOP AIDS/Chicago, and was a founding board member of the gay group IMPACT. She has also supported Test Positive Aware Network, Equality Illinois, Lambda Legal, and the Center on Halsted.