Alma was the youngest of seven children, born when her mother (whose name is reported as Anna, Zara, and Edith Sarah) was nearly fifty. Of the six other children, three girls survived infancy. The eldest, Cecile (eighteen years older than Alma), ran the household and reared the others. Her father (reported as Israel, Leon, and Louis Saul), who died when Alma was two, was an opera buff: His older daughters told stories of his attending a performance after hauling produce all day and returning home to sing the entire score for his family. 

By 1890, Cecile Fiersohn, who had paid her own passage to the United States, had saved enough from her sweatshop earnings to send for her mother and sisters. Alma attended public school through eighth grade on New York’s Lower East Side and subsequently worked as an office clerk. Although some accounts indicate that she attended the Normal School (later Hunter College) and Union College, an inspection of school records appears to show that this was not the case. On May 25, 1902, she married Bernard Gluck, an insurance agent (some sources record his name as Glick). They divorced in 1912. Their daughter, Abigail, became the writer Marcia Davenport. 

Although she had a beautiful voice as a girl and learned to play piano, Gluck began vocal training only as an adult. In 1906, a business associate of her husband’s who had heard her sing arranged for her to take voice lessons. She also studied in Europe accompanied only by her daughter. An anecdote tells of Gluck’s serendipitous encounter with Arturo Toscanini. The conductor heard her sing when she arrived for a lesson at her teacher’s house while he and the manager of New York’s Metropolitan Opera were dining there. Both men were skeptical of the teacher’s motives—Gluck was a beautiful woman—until they heard the soprano warming up. Toscanini then insisted on accompanying her himself. (Marcia Davenport writes that the meeting was no accident: Gluck’s teacher engineered it, and Gluck was aware of her listener’s identity.) After a formal audition, Gluck was hired. Toscanini conducted the performance in which she made her debut (under the name Alma Gluck), Massenet’s Werther. It was presented by the Metropolitan Opera but took place at the New Theatre on November 16, 1909. During Gluck’s first season with the company, she sang eleven minor roles in three languages. 

Gluck, however, was not fond of opera’s theatrical nature. Less than a year after her operatic debut, she sang her first recital. By 1911, she had found her niche as a concert artist, a venue in which her charm and elegance were more readily apparent. After leaving the Metropolitan in 1913, she studied in Berlin and Paris. By the following year, Gluck was the most popular concert singer in the United States. She performed in all forty-eight states (traveling later in a private railway car) as a recitalist and orchestral soloist. Until 1921, she gave almost 100 recitals a season, and she continued to perform until 1925. Between 1911 and 1919, Gluck made 124 recordings. Although many were classical, she was famous for her renditions of American folk songs. She was a best-selling artist: Between 1914 and 1918 alone her recording royalties totaled $600,000. 

On June 15, 1914, Gluck was married in London to violinist Efrem Zimbalist. They had two children, Maria Virginia Goelet (b. 1915), and Efrem, Jr. (b. 1918), the actor, writer, and director. Husband and wife often appeared together in concert, and several of Gluck’s recordings feature Zimbalist’s violin obbligatos. In her retirement, Gluck devoted herself to her family and to the artistic world: She was a founder of the American Guild of Musical Artists and was famous for her support of musical causes as well as for her soirées. In 1930, Alma Gluck was diagnosed with an incurable liver ailment. She died in New York on October 27, 1938. 

If Gluck identified herself with the Jewish community as an adult, there appears to be no record of it, and she developed strong ties to the Episcopal church. She left bequests to Union Chapel on Fishers Island, New York, where she had a summer home, and to St. Thomas Church in New York City. In addition, all three of her children were baptized: Maria Virginia and Efrem, Jr. at St. Thomas (in 1921), and Marcia Davenport (in 1922) at the boarding school run by Episcopal nuns to which she had been sent, with her mother as one of her sponsors. Gluck herself, Davenport writes, “drifted on the agnostic sea-of-consent where so many barks float or founder or merely keep on circling, but she did not think that right for her children.”