When she was very young, the family moved to Brooklyn, New York, and she became involved in acting as a child, performing her first stage role at the age of six.

[2] In the spring of 1909, Gertrude moved with her husband to New Rochelle, New York where they established Thanhouser Company as an independent motion picture studio; it was the first to be organized by leaders with strong theatrical training.

She received co-scenario writing credit with brother-in-law, Lloyd Lonergan, for the screen adaptation of Shakespeare's The Winter's Tale.

Behind the scenes, Gertrude was heavily involved in scenario development, creation of mise en scène and film editing.

In 1912, the Thanhousers sold their shares in the company to Charles J. Hite of Mutual Film Corporation for $250,000 and retired from the industry.