An eclogue is a poem in a classical style on a pastoral subject. Poems in the genre are sometimes also called bucolics.

The etymology of the word is contested; one theory relates it to Greek eklegein (εκλεγειν), meaning "a choice," and another derives it from aix (αιξ), "goat," and logos (λογος), "speech," meaning a dialogue between shepherds. Many eclogues are in fact cast in the form of dialogues between pastoral characters.

The Greek poets Hesiod, with his Works and Days, and Theocritus, in his Idylls, started the genre. Hesiod's poem is a matter-of-fact description of the seasonal life of a farmer, relatively sober and realistic; its literary descendant is Ovid's Fasti. The Idylls of Theocritus were much more influential; they were idealized fantasies portraying the life of the shepherds of Arcadia as a life of utopian leisure, taken up mostly by erotic pastimes. The Latin poet Virgil took Theocritus as his master, not Hesiod, in composing his own Eclogues, and most later attempts at producing work in the genre have followed Vergil's lead.

In English literature, Edmund Spenser's The Shepheardes Calender belongs to the genre, as does Sir Philip Sidney's Arcadia. Alexander Pope produced a series of eclogues in imitation of Vergil. The Spanish poet Garcilaso de la Vega also wrote eclogues in the Vergilian style. In French, Pierre de Ronsard wrote a series of eclogues under the title Les Bucoliques, and Clément Marot also wrote in the genre.