Aggadah (Hebrew: אַגָּדָה, romanized: Aggāḏā, or הַגָּדָה Haggāḏā; Jewish Babylonian Aramaic: אֲגַדְתָּא, romanized: Aggāḏṯā; 'tales', 'legend', 'lore') is the non-legalistic exegesis which appears in the classical rabbinic literature of Judaism, particularly the Talmud and Midrash. In general, Aggadah is a compendium of rabbinic texts that incorporates folklore, historical anecdotes, moral exhortations, and practical advice in various spheres, from business to medicine.

The Hebrew word haggadah (הַגָּדָה) is derived from the Hebrew root נגד, meaning "declare, make known, expound", also known from the common Hebrew verb להגיד.

The majority scholarly opinion is that the Hebrew word aggadah (אַגָּדָה) and corresponding Aramaic aggadta (אֲגַדְתָּא) are variants of haggadah based on a common linguistic shift from haphalah to aphalah forms. However, a minority of scholars believe that these words derive from a separate Aramaic root נגד meaning "draw, pull, spread, stretch" (corresponding to the Hebrew root משך or נטה).

According to the latter etymology, aggadah may be seen as "the part of the Torah which draws man towards its teachings", or the teachings which strengthen one's religious experience and spiritual connections, in addition to explaining texts. (See similar re Masorah – in the sense of "tradition" – at Masoretic Text § Etymology.)

The Aggadah is part of Judaism's Oral Torah, the traditions providing the authoritative interpretation of the Written Torah. In this context, the widely-held view in rabbinic literature is that the Aggadah is in fact a medium for the transmission of fundamental teachings (Homiletic Sayings—מאמרים לימודיים‎) or for explanations of verses in the Hebrew Bible (Exegetic Sayings—מאמרים ביאוריים‎). Rabbinic thought, therefore, understands much of the Aggadah as containing a hidden, allegorical dimension, in addition to its overt, literal sense. In general, where a literal interpretation contradicts rationality, the rabbis seek an allegorical explanation: "We are told to use our common sense to decide whether an aggada is to be taken literally or not" (Carmell, 2005).

Moshe Chaim Luzzatto (1707–1746), discusses this two-tiered, literal-allegorical mode of transmission of the Aggadah in his Discourse on the Haggadot. He explains that the Oral Law, in fact, comprises two components: the legal component (חלק המצוות‎), discussing the mitzvot and halakha; and "the secret" component (חלק הסודות‎), discussing the deeper teachings. The Aggadah, along with the Kabbalah, falls under the latter. The rabbis of the Mishnaic era (c. 10 – c. 220 CE) believed that it would be dangerous to record the deeper teachings in an explicit, mishnah-like, medium. Rather, they would be conveyed in a "concealed mode" and via "paradoxes". (Due to their value, these teachings should not become accessible to those "of bad character"; and due to their depth they should not be made available to those "not schooled in the ways of analysis".) This mode of transmission nevertheless depended on consistent rules and principles such that those "equipped with the keys" would be able to unlock their meaning; to others they would appear as non-rational or fantastic.

In line with the above, Samuel ibn Naghrillah (993–1056), in his "Introduction to the Talmud", states that "Aggadah comprises any comment occurring in the Talmud on any topic which is not a commandment (i.e. which is not halachic) and one should derive from it only that which is reasonable." As regards this, Maimonides (1138–1204), in his preface to the tenth chapter of Tractate Sanhedrin (Perek Chelek), describes three possible approaches to the interpretation of the Aggadah:

Maimonides' approach is also widely held amongst the non-rationalistic, mystical streams of Judaism—thus, for example, Isaiah Horowitz (c. 1555 – 1630) holds that "none of these sometimes mind-boggling 'stories' are devoid of profound meaning; if anyone is devoid of understanding, it is the reader" (Shnei Luchos HaBris, introduction). See also the Maharal's approach.