Judith Eisenstein (née Kaplan; September 10, 1909 – February 14, 1996) was an author, musicologist, composer, theologian and the first person to celebrate a bat mitzvah publicly in America (see below).

[1] Judith, the eldest of four daughters born to Lena (née Rubin) and Rabbi Mordecai Kaplan (who was the founder of the Reconstructionist branch of Judaism[2]), was the first person to celebrate a bat mitzvah publicly in America, which she did on March 18, 1922, aged 12, at her father’s synagogue the Society for the Advancement of Judaism in New York City.

[4] Until this time women did not engage in public reading of the Torah and a Jewish girl's transition from child to adult was not reflected in synagogue ceremonies.

Various feminist and Jewish leaders, including Betty Friedan, Letty Cottin Pogrebin, Ruth W. Messinger, and Elizabeth Holtzman were present.

She earned bachelor's and master's degrees from Columbia University and studied at the Institute of Musical Art, now the Juilliard School.