Ella graduated from Northwood Academy at 15, after making an impression there as a public speaker. After a year at Plymouth Normal School and a few years of teaching in country schools to earn money for tuition, she entered Bates College. She became the first female to serve on the debate team and the first woman editor of the school paper.
In 1884 she graduated with honors from Bates College in Maine. In her schooldays she often gave dramatic entertainments and acted in amateur theatrical organizations. She received her degree of A. M. in June 1888, from Bates and after hesitating between school teaching and law as a profession, she decided to study law. She entered the office of Judge Burnham, in Manchester, New Hampshire. In 1889 she moved to Iowa, where she taught classes in French and German in a school for a short time. She next went to Salt Lake City, Utah, where she took a position as teacher. While there, she received an offer of a larger salary to return to the Iowa University, in which she had taught.
However, Haskell moved to Helena, Montana, During her first year in Helena she served as secretary of a lumber company. Later she was invited to take a position as a school principal and teacher in the main school. Not long after reaching Helena she decided to finish her law course, and she entered a law office. Against the advice of her friends, she resigned from the school and moved to Butte where she resumed her study of law.
Breaking into the legal profession was not easy for Montana's first woman lawyer. Ella begged a friend to let her handle some bill-collecting cases for him. “About all you're capable of,” he told her “is to collect three umbrellas from folks that never returned them to me.” When Ella came back a few hours later with the long-lost umbrellas, she demanded and got fifty cents in payment and the amused respect of her friend who then hired her for more important legal business. Ella was launched on what became a very successful career.
At that time, women were not permitted to practice in the courts of Montana, so Ella set to work to get a bill through the Legislature. The law passed in 1889, and in January 1890, Ella Knowles was admitted to the Montana bar and admitted to practice before the Supreme Court of Montana. “Women should have the rights of electors as they are required to pay taxes. If it was unjust for our fathers to be taxed by Great Britain without representation, it is unjust to tax women today without representation.”
While studying law she acted as collector, and then took up attachment and criminal cases, and she received several divorce cases, which she handed over to her principal, Mr. Kinsley. Haskell formed a law partnership with Mr. Kinsley and did large business. On April 18, 1890, she was admitted to practice before the District Court of the United States, and on April 28 she received credentials that enabled her to practice before the Circuit Court of the United States. In 1888 she was appointed a notary public by Governor Leslie, and she was the first woman to hold such an office in Montana. In 1892, 22 years before Montana women received the right to vote, Knowles ran for state Attorney General after being nominated by the Populist Party, becoming the first woman in the nation to run for that office. Although she narrowly lost the election, she was nominated to be Assistant Attorney General by the victor, Henri Haskell, a Republican. Haskell and Knowles later married.
In 1896 Haskell became the first Montana woman to be elected to a political convention, the Populist party. In 1902, Haskell divorced her husband, and moved to Butte, Montana where she became a very successful attorney as she invested in mining property and successfully conducted several important mining deals. One fee of $10,000 was said to be the largest ever paid to a woman lawyer. She went on to argue and win cases before the United States Circuit Court and the United States Supreme Court.
Ella lived alone in a hotel apartment near her office in Butte; and it was there that she died in 1911 of complications that followed a throat infection. Her obituary in the Butte Evening News said that various women's organizations had helped to make funeral arrangements, since she ‘had not one relative in the state.’ There was praise for her quiet dignity, splendid talents, convincing eloquence and womanly attributes.
The obituary in The Boston Transcript of February 11, 1911 concludes “In her social life she was a charming example of the eternal feminine, enjoying to the full pretty gowns, cards, and the talk and laughter of social occasions.”