Siff was born in The Bronx, New York City. Her father is Jewish (from a family from Russia), and her mother is of Irish and Swedish descent; she has said that she feels "culturally Jewish". She is an alumna of The Bronx High School of Science and of Bryn Mawr College, where she majored in English and graduated in 1996.

Siff  is an alumnus of the prestigious Bronx High School of Science and Bryn Mawr College, where she majored in English and graduated in 1996. She further holds an MFA in acting from New York University's Tisch School of the Arts, one of the nation's best Graduate Acting Programs. Siff gained extensive experience working in regional theater before pursuing a television career. In 1998, long before she became a presence on our television screens, she won an Excellence in Theater Barrymore Award for her outstanding performance in Henrik Ibsen's Ghosts staged with the Lantern Theater Company.

Maggie Siff is an American actress. Her most notable television roles have included department store heiress Rachel Menken Katz on the AMC drama Mad Men, Dr. Tara Knowles on the FX drama Sons of Anarchy 

Siff  is an alumnus of the prestigious Bronx High School of Science and Bryn Mawr College, where she majored in English and graduated in 1996. She further holds an MFA in acting from New York University's Tisch School of the Arts, one of the nation's best Graduate Acting Programs. Siff gained extensive experience working in regional theater before pursuing a television career.

In 1998, long before she became a presence on our television screens, she won an Excellence in Theater Barrymore Award for her outstanding performance in Henrik Ibsen's Ghosts staged with the Lantern Theater Company. Her television debut was a 2004 appearance as a speaker for Alcoholics Anonymous on a season 2 episode of the series Rescue Me. This was later followed through with brief roles in Funny People, Grey's Anatomy, Law and Order: Special Victims Unit, and Law and Order. Her role as Rachel Menken on the Mad Men series from 2007 to 2008 earned her a combined nomination with the rest of the show's cast, for a SAG Award. In 2013, Siff announced that she was expecting her first child with her husband, Paul Ratliff.