The dating of Beowulf has attracted considerable scholarly attention; opinion differs as to whether it was first written in the 8th century, whether it was nearly contemporary with its 11th century manuscript, and whether a proto-version (possibly a version of the Bear's Son Tale) was orally transmitted before being transcribed in its present form. Albert Lord felt strongly that the manuscript represents the transcription of a performance, though likely taken at more than one sitting. J. R. R. Tolkien believed that the poem retains too genuine a memory of Anglo-Saxon paganism to have been composed more than a few generations after the completion of the Christianisation of England around AD 700, and Tolkien's conviction that the poem dates to the 8th century has been defended by scholars including Tom Shippey, Leonard Neidorf, Rafael J. Pascual, and Robert D. Fulk. An analysis of several Old English poems by a team including Neidorf suggests that Beowulf is the work of a single author.
The claim to an early 11th-century date depends in part on scholars who argue that, rather than the transcription of a tale from the oral tradition by an earlier literate monk, Beowulf reflects an original interpretation of an earlier version of the story by the manuscript's two scribes. On the other hand, some scholars argue that linguistic, palaeographical (handwriting), metrical (poetic structure), and onomastic (naming) considerations align to support a date of composition in the first half of the 8th century; in particular, the poem's apparent observation of etymological vowel-length distinctions in unstressed syllables (described by Kaluza's law) has been thought to demonstrate a date of composition prior to the earlier ninth century. However, scholars disagree about whether the metrical phenomena described by Kaluza's Law prove an early date of composition or are evidence of a longer prehistory of the Beowulf metre; B.R. Hutcheson, for instance, does not believe Kaluza's Law can be used to date the poem, while claiming that "the weight of all the evidence Fulk presents in his book[b] tells strongly in favour of an eighth-century date."
From an analysis of creative genealogy and ethnicity, Craig R. Davis suggests a composition date in the AD 890s, when King Alfred of England had secured the submission of Guthrum, leader of a division of the Great Heathen Army of the Danes, and of Aethelred, ealdorman of Mercia. In this thesis, the trend of appropriating Gothic royal ancestry, established in Francia during Charlemagne's reign, influenced the Anglian kingdoms of Britain to attribute to themselves a Geatish descent. The composition of Beowulf was the fruit of the later adaptation of this trend in Alfred's policy of asserting authority over the Angelcynn, in which Scyldic descent was attributed to the West-Saxon royal pedigree. This date of composition largely agrees with Lapidge's positing of a West-Saxon exemplar c.900.
The location of the poem's composition is intensely disputed. In 1914, F.W. Moorman, the first professor of English Language at University of Leeds, claimed that Beowulf was composed in Yorkshire, but E. Talbot Donaldson claims that it was probably composed during the first half of the eighth century, and that the writer was a native of what was then called West Mercia, located in the Western Midlands of England. However, the late tenth-century manuscript "which alone preserves the poem" originated in the kingdom of the West Saxons – as it is more commonly known.