Without a doubt, ʿAttar's most famous work today is the Conference of the Birds. Since 1863 it has been translated multiple times into European languages, and it has recently inspired two original illustrated books as well as multiple stage performances. It is also easily ʿAttar's most studied work. Its academic and non-academic popularity is largely due to its allegorical frame-tale, which is commonly summarised as follows: a hoopoe leads a group of birds on a dangerous journey towards their king, the Simorgh, who resides on Mount Qaf at the edge of the world. To arrive there, they must journey through seven valleys. Many of the birds perish along the way, and when they finally encounter the Simorgh, only thirty of them are left alive. When those thirty remaining birds gaze on the Simorgh, they are astonished to see themselves reflected in the Simorgh, and the Simorgh reflected in themselves. They are ontologically linked to the Simorgh, who nevertheless remains utterly transcendent. In this way, they experience effacement (fanaʾ) in the divine, which is encapsulated in the poem's central pun on ‘thirty birds’ (si-morgh) and ‘Simorgh’. The poem is thus an allegory of the sufi path, in which the birds symbolise sufi seekers, the hoopoe their pir and the Simorgh, God.

The above summary, however, corresponds only to a portion of the frame-tale. Before they actually set out on the quest, the birds voice objections and concerns about the proposed journey, which the hoopoe proceeds to demolish; they then ask a series of questions about spiritual virtues and vices, to which the hoopoe responds in the fashion of a preacher delivering a homiletic assembly. These are more than brief preliminaries introducing the quest. In fact, the hoopoe's homiletic performances are, in many ways, the heart of the masnavi. They represent the vast majority of the poem (approximately 88 per cent of its total length), and it is through these performances, the contents of which are recapitulated by ʿAttar for the benefit of his readers, that the birds are rendered fit for their journey. Only at the very end of the poem do they actually set out on the path towards the Simorgh, and the events of the journey are only briefly alluded to before their final admission to the divine presence.