Mary-Kate Olsen made her acting debut in 1987 at nine months old sharing the role of the youngest daughter, Michelle Tanner with her twin sister Ashley on Full House. The show was a tremendous hit, and the Olsen twins grew up in front of the American viewing public.
By the age of twelve, the girls had starred in home videos, feature films, multi-media entertainment and another TV series, Two of a Kind. Under the name Dualstar Entertainment, they produced several straight-to-video movies, a line of musical detective videos entitled The Adventures of Mary-Kate & Ashley, and the enormously successful You're Invited to Mary-Kate and Ashley's party tapes. They have also introduced a series of companion books to accompany the videos. In 1993, Our First Video went to the top of the Billboard video music chart, and was followed shortly by I Am The Cute One and Brother for Sale. The twins made their big screen debut in 1995 in It Takes Two.
In addition to acting, the Olsens have become a huge force in girl marketing. Products bearing their names, including computer games, dolls, and an enormously popular clothing line for Wal-Mart, are estimated to generate about $1 billion in retail sales alone per year.
Mary-Kate and Ashley announced plans to attend New York University in the fall of 2004. Shortly after the news, Mary-Kate checked herself into a rehabilitation facility for the eating disorder, anorexia. In the wake of rumors about Mary-Kate's health, the twins released their next feature film, New York Minute.
In 2005 the sisters began appearing together in the Badgley Mischka ad campaign. Mary-Kate also ended her relationship with Greek shipping heir Stavros Niarchos III. The break-up, combined with the changes at Dualstar, led Mary-Kate quit school and return to California to focus on business ventures with her company.
Two years later, in 2007, Forbes magazine ranked Mary-Kate and Ashley Olsen as the eleventh-richest women in entertainment. Their estimated net worth sits at nearly $100 million.
In January of 2008, Mary-Kate made headlines when her close friend, actor Heath Ledger, died of a prescription drug overdose. She remains silent on the matter, but sources say Ledger's staff contacted Mary-Kate through a speed-dial function on Ledger's cell phone. Mary-Kate then called her security staff in New York to investigate the matter. Ledger was pronounced dead later that day.
In October of 2008, the twins released the book Influence, a work introducing readers to the artists and designers who have influenced the Olsens over the last decade. Released through a division of the Penguin Young Readers Group, the work features figures such as Christian Louboutin, Lauren Hutton and Bob Colacello. It became an instant best seller, and the twins are currently wrapping up a promotional tour for the book.
Mary-Kate has embarked on a solo fashion project with celebrity stylists Jane Magnitude and Fred Holston.