The Musar movement (also Mussar movement) is a Jewish ethical, educational and cultural movement that developed in 19th century Eastern Europe, particularly among Orthodox Lithuanian Jews. The Hebrew term Musar (מוּסַר), is from the book of Proverbs 1:2 meaning moral conduct, instruction or discipline. The term was used by the Musar movement to refer to efforts to further ethical and spiritual discipline. The Musar Movement made significant contributions to Jewish ethics.

The Musar movement arose among the non-Hasidic Orthodox Lithuanian Jews, and became a trend in their yeshivas. The movement's founding is attributed to Rabbi Yisrael Lipkin Salanter (1810–1883), although the roots of the movements drew on ideas previously expressed in classical Musar literature. Prior to the founding of the Musar movement, musar was a practice of the solitary seeker; thanks to Salanter, it became the basis for a popular social/spiritual movement.

Yisrael Lipkin Salanter, a promising young rabbi with exceptional knowledge of Jewish law living in Salantai, Lithuania, was initially inspired to dedicate his life to the cause of spreading Musar by his teacher Rabbi Yosef Zundel Salant (1786–1866). Zundel Salant was a student of Rabbis Chaim Volozhin and Akiva Eiger whose profoundly good-hearted and humble behavior and simple lifestyle attracted Yisrael Salanter's interest, and Zundel Salant allegedly urged Salanter to focus himself on Musar.