thumb|Cover of the first edition of Mesillat Yesharim.
Mesillat Yesharim or Mesillas Yeshorim () is an ethical (musar) text composed by the influential Rabbi Moshe Chaim Luzzatto (1707–1746). It is different from Luzzato's other writings, which are more philosophical.
Mesillat Yesharim was written and published in Amsterdam. The earliest known manuscript version, written in 1738, was arranged as a dialogue between a hakham (wise man) and a hasid (pious person). Before publication, it was rearranged to have only one speaker. The dialogue version often sheds light on the more well-known version.
Mesillat Yesharim is probably Luzzato's most influential work, widely learned in virtually every yeshiva since formal study of musar texts was introduced to the yeshiva curriculum by the Musar movement of Rabbi Yisroel Salanter.
Aim of the work
The aim of this work extends beyond the achievement of the perfection of human character in the service of the divine. Its stated aim is to remind the reader of one's deepest obligations in this regard, as well as to encourage the centrality of the deep study of this subject matter in one's daily life. Unlike much of the Musar literature, which is ordered according to the authors' own lists of character traits, Luzzato builds his work on a baraita in the name of the sage Pinchas ben Yair, whose list goes in order of accomplishment:
Within each step, Luzzatto explains the step itself, its elements, how it can be acquired, and what might detract from its acquisition. For example, Watchfulness can be acquired by setting aside time for introspection, but it can be impaired by excessive mundane responsibilities, bad company, or a cynical stance in life. The same pattern is used for every trait mentioned.
Luzzatto's expressed goal is to condition the reader to accept a disciplined approach to "restrain animal instincts" and encourage "the divine spark in every human into a bright, warming flame", according to Trude Weiss-Rosmarin.
American rabbi Mordecai Kaplan published the first English translation of Mesillat Yesharim through the Jewish Publication Society of America in 1936.