She received a Bachelor of Science degree from the University of Kansas in 1971 and a Juris Doctor from the University of Minnesota Law School in 1974.

She was a law clerk to Gerard D. Reilly and Hubert Pair, both of the District of Columbia Court of Appeals from 1974 to 1975.

She was an Assistant United States Attorney of the District of Minnesota from 1976 to 1983.

Montgomery became a United States magistrate judge of the United States District Court for the District of Minnesota in 1994.

On November 27, 1995, Montgomery was nominated by President Bill Clinton to a seat on the United States District Court for the District of Minnesota vacated by Judge Diana E. Murphy.