The Enchiridion or Handbook of Epictetus (Ancient Greek: Ἐγχειρίδιον Ἐπικτήτου, Enkheirídion Epiktḗtou) is a short manual of Stoic ethical advice compiled by Arrian, a 2nd-century disciple of the Greek philosopher Epictetus. Although the content is mostly derived from the Discourses of Epictetus, it is not a summary of the Discourses but rather a compilation of practical precepts. Eschewing metaphysics, Arrian focuses his attention on Epictetus's work applying philosophy to daily life. Thus, the book is a manual to show the way to achieve mental freedom and happiness in all circumstances.

The Enchiridion was well known in the medieval world and was specially adapted for use in Greek-speaking monasteries. In the 15th century it was translated into Latin, and then, with the advent of printing, into multiple European languages. It reached the height of popularity in the 17th century, in parallel with the Neostoicism movement.

The word "Enchiridion" (Ancient Greek: ἐγχειρίδιον) is an adjective meaning "in the hand" or "ready to hand". The word sometimes meant a handy sword, or dagger, but coupled with the word "book" (biblion, Greek: βιβλίον) it means a handy book or hand-book. Epictetus in the Discourses often speaks of principles which his pupils should have "ready to hand" (Greek: πρόχειρα). Common English translations of the title are Manual or Handbook.

The Enchiridion consists of fifty-three short chapters typically consisting of a paragraph or two, and appears to be a loosely-structured selection of maxims. It was compiled some time in the early 2nd century. Around half of the material in the Enchiridion has been shown to have been derived from the surviving four books of Discourses but variously modified. Some chapters appear to be reformulations of ideas which appear throughout the Discourses. Other parts are presumed to be derived from the lost Discourses.

The 6th-century philosopher Simplicius, in his commentary on the work, refers to a letter written by Arrian which prefaced the text. In this letter Arrian stated that the Enchiridion was selected from the Discourses of Epictetus according to what he considered to be most useful, most necessary, and most adapted to move people's minds. In his commentary, Simplicius divided the text into four distinct sections suggesting a graded approach to philosophy:

There are some puzzles concerning the inclusion of two chapters. Chapter 29, a one-page Discourse which compares the training needed to become a Stoic with the rigorous approach needed to become an Olympic victor, is practically word for word identical with Discourse iii. 15. Since it was omitted in one of the early Christian editions (Par), and not commented on by Simplicius, it may not have been in the original edition. Chapter 33 consists of a list of moral instructions, which are "not obviously related to Epictetus' normal Stoic framework."

The Enchiridion begins with the statement, "Of things, some depend upon ourselves, others do not depend upon ourselves." So it starts with announcing that the business and concern of the real self is with matters subject to its own control, uninfluenced by external chance or change. Epictetus makes a sharp distinction between our own internal world of mental benefits and harms and the external world beyond our control. Freedom is to wish for nothing which is not up to ourselves. When we are tried by misfortune, we should never let our suffering overwhelm our sense of inward mastery and freedom.

A constant vigilance is required, and one should never relax attention to one's reason, for it is judgements, not things, which disturb people.