Flanders was born in the Bronx, New York, as Marcia Weinraub to Dorothy (Lautman) and Ralph "Lefty" Weinraub.^[1][2] She attended New York University, where she studied retailing and journalism and was named Miss New York University in 1959.^[1][2]

Her career began in the retail sector, including roles at Gimbels department store.^[1][2] Later, she opened a boutique named Abracadabra in New York.^[1][2] Flanders adopted her professional name after meeting her partner, Chris Flanders, who suggested she change it from her birth name, Marcia.^[1][3]

In the 1970s, Flanders contributed to The SoHo News as a style editor.^[1] In 1982, she used her savings to launch Details, a publication initially focused on Downtown Manhattan's culture and lifestyle.^[1] The magazine, starting with a circulation of 10,000 copies, was known for its unique editorial approach, blending fashion, culture, and nightlife reporting.^[1] Flanders' tenure at Details ended two years after its acquisition by Advance Publications in 1988.^[1]

Following her career in publishing, Flanders transitioned to real estate in Hollywood, Los Angeles, working with her daughter Rosie.^[1][3] She died in 2022 in Los Angeles.^[1][4]