Ælfric gives away few autobiographical details in his writings, and we do not know the year of his birth or of his death, although by extrapolation from what we do know of his later career, we can deduce that he was probably born at some time in the 950s, and not later than 957. The language of his writings suggests strongly that he grew up in Wessex, and his later dealings with people of high rank in both the ecclesiastical and secular worlds, as well as his ultimate achievement of the rank of abbot, suggest that he did not come from the humblest of backgrounds. He does tell us on a number of occasions that he was educated at the monastic school at Winchester under the illustrious Æthelwold (bishop of Winchester 963–84), a fact of which he was clearly proud. He refers to himself in terms such as Ælfricus, alumnus Aðelwoldi, beneuoli et uenerabilis presulis, and even much later when he had become an abbot as Ælfricus abbas, Wintoniensis alumnus. Æthelwold's own Old English prose is renowned for its clarity and lack of ornamentation, as evidenced for instance in his translation of the Regula S. Benedicti, and it is difficult to believe that this did not have a major effect on the development of Ælfric's own style. Indeed, he makes clear how much he felt he owed to Æthelwold, and how far-reaching the influence of his school had been:

Whilst at Winchester, Ælfric became a monk and was ordained as a priest, presumably at the canonical age of 30. He tells us in the opening lines of the Old English preface to the first series of Catholic Homilies that he was subsequently sent by Ælfheah, bishop of Winchester from 984 to 1006, as mass-priest to the abbey of Cernel, now Cerne Abbas, Dorset, which had been founded, or perhaps re-founded, in 987 by Æthelmær, son of Æthelweard, ealdorman of the south-western counties (probably Somerset, Devon and Dorset). These two figures would remain important patrons of Ælfric for much of his career.