Atticism (meaning favouring Attica, the region that includes Athens) was a rhetorical movement that began in the first quarter of the first century BC; it may also refer to the wordings and phrasings typical of this movement, in contrast with spoken Greek, which continued to evolve in directions guided by the common usages of Hellenistic Greek.

Atticism was portrayed as a return to Classical methods after what was perceived as the pretentious style of the Hellenistic, Sophist rhetoric and called for a return to the approaches of the Attic orators.

Although the plainer language of Atticism eventually became as belabored and ornate as the perorations it sought to replace, its original simplicity meant that it remained universally comprehensible throughout the Greek world. This helped maintain vital cultural links across the Mediterranean and beyond. Admired and popularly imitated writers such as Lucian also adopted Atticism, so that the style survived until the Renaissance, when it was taken up by non-Greek students of Byzantine expatriates. Renaissance scholarship, the basis of modern scholarship in the west, nurtured strong Classical and Attic prejudices, continuing Attic snobbishness for another four centuries.

Represented at its height by rhetoricians such as Dionysius of Halicarnassus, and grammarians such as Herodian and Phrynichus Arabius at Alexandria, this tendency prevailed from the second century B.C. onward, and with the force of an ecclesiastical dogma controlled all subsequent Greek culture, even so that the living form of the Greek language, even then being transformed into modern Greek, was quite obscured and only occasionally found expression, chiefly in private documents, though also in popular literature.