In 2014, when Barbara Madeloni was elected president of the 116,000-member Massachusetts Teachers Association (MTA), she was both an improbable winner and an unapologetic leftist. A year earlier, the odds would have been a thousand to one against her election.

In MTA practice, the sitting vice-president ascended uncontested to the presidency; elections for vice-president were contested, but those for president almost never were. Madeloni had never served on the board of the statewide union, or on any of its committees, nor had she held office in her local union. She was a pure rank-and-file candidate.

As Madeloni is termed out of her tenure as MTA president, it’s worth reflecting on why and how she won, what she and the rest of the union accomplished, and the tasks for the MTA going forward. Her tenure offers lessons for union reformers, especially teachers, everywhere.