Aelred (also written Ailred, Æthelred and Ethelred) was born at Hexham in 1109, the son of one of the married priests then common in England. As a young man he served at the court of David, St Margaret's youngest son and soon King of Scotland, as a kind of page or companion to Prince Henry. King David loved the devout English youth, promoted him and wanted to make him a bishop, but Aelred chose instead to become a Cistercian (a strict reform of Benedictine monks begun at Cîteaux in 1098) monk at the newly founded abbey of Rievaulx in Yorkshire.

He was soon made master of novices and was long remembered for his extraordinary tenderness and patience with them. In 1143 he was sent with twelve monks to found a new abbey at Revesby in Lincolnshire, and in 1146 he was elected Abbot of Rievaulx. There he ruled 300 monks and headed all the Cistercian abbots in England. He seems to have had considerable influence over Henry II. He was present in Westminster Abbey at the translation of St Edward the Confessor in 1163, for which he wrote a Life of Edward. The next year he went on a mission to the Picts (the ancient people of northern Scotland) of Galloway, whose chief is said to have been so moved that he became a monk.

For his sermons he was called the English St Bernard, and he wrote treatises including the 'Mirror of Charity' and 'On Spiritual Friendship', as well as historical works. In his last years he was an example of heroic patience under one painful illness after another, and he ate so little that he was described as 'more like a ghost than a man'. His death is generally dated 12 January 1166, though the source notes that it may have been 1167.

He was of noble descent, and was born in the north of England, in 1109. Being educated in learning and piety, he was invited by David, the pious King of Scotland, to his court, made master of his household, and highly esteemed both by him and the courtiers.

​Ælred, Saint, Abbot of Rievaulx, homilist and historian (1109–66). St. Ælred, whose name is also written Ailred, Æthelred, and Ethelred, was the son of one of those married priests of whom many were found in England in the eleventh and twelfth centuries. He was born at Hexham, but at an early age made the acquaintance of David, St. Margaret's youngest son, shortly afterwards King of Scotland, at whose court he apparently acted for some years as a sort of page, or companion to the young Prince Henry. King David loved the pious English youth, promoted him in his household, and wished to make him bishop, but Ælred decided to become a Cistercian [strict Benedictine reform begun at Cîteaux in 1098] monk, in the recently founded abbey of Rievaulx in Yorkshire. Soon he was appointed master of novices, and was long remembered for his extraordinary tenderness and patience towards those under his charge. In 1143 when William, Earl of Lincoln, founded a new Cistercian abbey upon his estates at Revesby in Lincolnshire, St. Ælred was sent with twelve monks to take possession of the new foundation. His stay at Revesby, where he seems to have met St. Gilbert of Sempringham, was not of long duration, for in 1146 he was elected abbot of Rievaulx. In this position the saint was not only superior of a community of 300 monks, but he was head of all the Cistercian abbots in England. Causes were referred to him, and often he had to undertake considerable journeys to visit the monasteries of his order. Such a journey in 1153 took him to Scotland, and there meeting King David, for the last time, he wrote on his return to Rievaulx, where the news of David's death reached him shortly afterwards, a sympathetic sketch of the character of the late king. He seems to have exercised considerable influence over Henry II, in the early years of his reign, and to have persuaded him to join Louis VII of France in meeting Pope Alexander III, at Touci, in 1162. Although suffering from a complication of most painful maladies, he journeyed to France to attend the general chapter of his Order. He was present in Westminster Abbey, at the translation [the solemn moving of a saint’s relics to a new shrine] of St. Edward the Confessor, in 1163, and, in view of this event, he both wrote a life of the saintly king and preached a homily in his praise. The next year Ælred undertook a mission to the barbarous Pictish tribes of Galloway, where their chief is said to have been so deeply moved by his exhortations that he became a monk. Throughout his last years Ælred gave an extraordinary example of heroic patience under a succession of infirmities. He was, moreover, so abstemious that he is described as being "more like a ghost than a man." His death is generally supposed to have occurred 12 January, 1166, although there are reasons for thinking that the true year may be 1167. St. Ælred left a considerable collection of sermons, the remarkable eloquence of which has earned for him the title of the English St. Bernard. He was the author of several ascetical treatises, notably the "Speculum Charitatis," also a compendium of the same (really a rough draught from which the larger work was developed), a treatise "De Spirituali Amicitiâ," and a certain letter to an anchoress. All these, together with a fragment of his historical work, were collected and published by Richard Gibbons, S.J., at Douai, in 1631. A fuller and better edition is contained in the fifth volume of the "Bibliotheca Cisterciensis" of Tissier, 1662, from which they have been printed in P. L., vol. CXCV. The historical works include a "Life of St. Edward," an important account of the "Battle of the Standard" (1138), an incomplete work on the genealogy of the kings of England, a tractate "De Sanctimoniali de Watton" (About the Nun of Watton), a "Life of St. Ninian," a work on the "Miracles of the Church of Hexham," an account of the foundations of St. Mary of York and Fountains Abbey, as well as some that are lost. No complete edition of Ælred's historical opuscula has ever been published. A few were printed by Twysden in his "Decem Scriptores," others must be sought in the Rolls Series or in Raine's "Priory of Hexham" (Surtees Society, Durham, 1864).

An anonymous Latin Life of St. Ælred is printed by the Bollandists [Jesuit scholars who since the 1600s have critically studied the lives of the saints], Acta SS., January, vol. II; while other materials may be gathered from Raine, Priory of Hexham, and from Ælred's own writings. An excellent short biography was compiled by Father Dalgairns for Newman's series of Lives of the English Saints, 1845 (new ed., London, 1903); Dict. of Nat. Biog. s. v. Ethelred (XVIII, 33–35); Baring-Gould, Lives of the Saints, I, and the great Cistercian collections of Henriquez and Manrique.