Horace Meyer Kallen was born on August 11, 1882, in the town of Bernstadt, Prussian Silesia (now Bierutów, Lower Silesian Voivodeship, Poland).
[2] But after teaching English at Princeton for two years, his contract was not renewed, and he returned to Harvard for graduate study and worked as Santayana's assistant.
He lectured in philosophy at Harvard from his graduation until 1911, occasionally working as a logic instructor at Clark College in Worcester, Massachusetts.
In 1911, he moved to teach philosophy at the University of Wisconsin–Madison until 1918, when he was named a professor at The New School in New York City as a founding member, where he remained for the rest of his career.
He served on congressional committees on international peace and was a part of many think tanks and study groups on questions ranging from philosophy and law to labor relations.