The daughter of two law school graduates, Stein grew up in the Capital District of New York.
She graduated from Macalester College, with Phi Beta Kappa honors. She started law school at the Minnesota Law School, and after her first year, transferred to Albany Law School for her last two years, when she earned her law degree in 1981, and was ranked second in her class.
Stein worked in a paid legal internship during her last year at Albany Law. After law school, Stein first worked as a law clerk at Schenectady County Family Court.
She was in private practice for almost 14 years, starting as an associate and later a partner, at the Albany, New York law firm of McNamee, Lochner, Titus & Willams. She re-entered government service as an Albany City court judge in early 1997.
Stein served on the Albany Law School board of trustees.
She was elected to the State Supreme Court, Third Judicial District in 2001, and started her service on that trial bench on January 1, 2002. She was appointed, in February 2008, to fill a vacancy as an Associate Justice of the Appellate Division of the Supreme Court, Third Judicial Department. (Eliot Spitzer was the Governor at the time, a month before he resigned.)
Her selection to New York State's Court of Appeals, by Governor Cuomo, happened in late 2014. Judge Victoria A. Graffeo applied to the New York State Commission on Judicial Nominations to be considered for appointment to a second term. The Commission included Graffeo on its list of seven candidates for the position, but Governor Andrew Cuomo declined to reappoint Graffeo and instead selected Justice Stein for the position. Stein's nomination was confirmed by the New York State Senate on February 9, 2015.
Although most such appellate Judges have 14-year terms, Judge Stein will be forced into retirement at the age of 70, by a provision of the New York Constitution, on December 31, 2026.