Broadway in 1912, when she was cast as Dolores Pennington in Widow By Proxy which ran for 88 performances through early 1913 at George M. Cohan's Theatre on Broadway. During this same period she appeared on stages throughout the Northeastern United States as a member of Sylvester Poli's stock theater company, The Poli Players. She continued to achieve acclaim for her stage work, playing a number of starring roles, including the lead in Madame Butterfly. By 1914, she was back on the silver screen, as Emily Mason in the film Mrs. Black is Back. During World War I, Blandick performed some overseas volunteer work for the American Expeditionary Force in France. She also continued to act on stage and occasionally in silent pictures. In 1924, she earned rave reviews for her supporting role in the Pulitzer Prize winning play Hell-Bent Fer Heaven, which ran for 122 performances at the Klaw Theatre in New York (later renamed CBS Radio Playhouse No. 2). In 1929, Blandick moved to Hollywood. By the 1930s, she was well known in theatrical and film circles as an established supporting actress. Though she landed roles like Aunt Polly in the 1930 film Tom Sawyer (a role she reprised in the 1931 film Huckleberry Finn), she spent much of the decade as a character actor, often going uncredited. In Pre-Code films she often played mothers, including those of characters played by Joan Crawford (Possessed) and Joan Blondell (Three on a Match). At a time when many actors were permanently attached to a single studio, she played a wide number of bit parts for almost every major Hollywood studio (though she would later be under contract with 20th Century Fox). In 1930, she acted in nine films. In 1931 she was in thirteen films. As is the case with some other busy character actors, it is difficult to make an exact tally of the films in which Blandick appeared, but a reasonable estimate would fall between 150 and 200. The Wizard of Oz and later years In 1939, Blandick landed her most memorable minor role – Aunt Em in MGM's classic The Wizard of Oz. Though it was a small part (Blandick filmed all her scenes in a single week), the character was an important symbol of protagonist Dorothy's quest to return home to her beloved aunt and uncle. (Aunt Em and Uncle Henry are the only characters from