Henry I, the most resilient of the Norman kings (his reign lasted thirty-five years), was nicknamed "Beauclerc" (fine scholar) for his above average education. During his reign, the differences between English and Norman society began to slowly evaporate. Reforms in the royal treasury system became the foundation upon which later kings built. The stability Henry afforded the throne was offset by problems in succession: his only surviving son, William, was lost in the wreck of the White Ship in November 1120.

The first years of Henry's reign were concerned with subduing Normandy. William the Conqueror divided his kingdoms between Henry's older brothers, leaving England to William Rufus and Normandy to Robert. Henry inherited no land but received £5000 in silver. He played each brother off of the other during their quarrels; both distrusted Henry and subsequently signed a mutual accession treaty barring Henry from the crown. Henry's hope arose when Robert departed for the Holy Land on the First Crusade; should William die, Henry was the obvious heir. Henry was in the woods hunting on the morning of August 2, 1100 when William Rufus was killed by an arrow. His quick movement in securing the crown on August 5 led many to believe he was responsible for his brother's death. In his coronation charter, Henry denounced William's oppressive policies and promising good government in an effort to appease his barons. Robert returned to Normandy a few weeks later but escaped final defeat until the Battle of Tinchebrai in 1106; Robert was captured and lived the remaining twenty-eight years of his life as Henry's prisoner.

Henry was drawn into controversy with a rapidly expanding Church. Lay investiture, the king's selling of clergy appointments, was heavily opposed by Gregorian reformers in the Church but was a cornerstone of Norman government. Henry recalled Anselm of Bec to the archbishopric of Canterbury to gain baronial support, but the stubborn Anselm refused to do homage to Henry for his lands. The situation remained unresolved until Pope Paschal II threatened Henry with excommunication in 1105. He reached a compromise with the papacy: Henry rescinded the king's divine authority in conferring sacred offices but appointees continued to do homage for their fiefs. In practice, it changed little - the king maintained the deciding voice in appointing ecclesiastical offices - but it a marked a point where kingship became purely secular and subservient in the eyes of the Church.

By 1106, both the quarrels with the church and the conquest of Normandy were settled and Henry concentrated on expanding royal power. He mixed generosity with violence in motivating allegiance to the crown and appointing loyal and gifted men to administrative positions. By raising men out of obscurity for such appointments, Henry began to rely less on landed barons as ministers and created a loyal bureaucracy. He was deeply involved in continental affairs and therefore spent almost half of his time in Normandy, prompting him to create the position of justiciar - the most trusted of all the king's officials, the justiciar literally ruled in the king's stead. Roger of Salisbury, the first justiciar, was instrumental in organizing an efficient department for collection of royal revenues, the Exchequer. The Exchequer held sessions twice a year for sheriffs and other revenue-collecting officials; these officials appeared before the justiciar, the chancellor, and several clerks and rendered an account of their finances. The Exchequer was an ingenious device for balancing amounts owed versus amounts paid. Henry gained notoriety for sending out court officials to judge local financial disputes (weakening the feudal courts controlled by local lords) and curb errant sheriffs (weakening the power bestowed upon the sheriffs by his father).

The final years of his reign were consumed in war with France and difficulties ensuring the succession. The French King Louis VI began consolidating his kingdom and attacked Normandy unsuccessfully on three separate occasions. The succession became a concern upon the death of his son William in 1120: Henry's marriage to Adelaide was fruitless, leaving his daughter Matilda as the only surviving legitimate heir. She was recalled to Henry's court in 1125 after the death of her husband, Emperor Henry V of Germany. Henry forced his barons to swear an oath of allegiance to Matilda in 1127 after he arranged her marriage to the sixteen-year-old Geoffrey of Anjou to cement an Angevin alliance on the continent. The marriage, unpopular with the Norman barons, produced a male heir in 1133, which prompted yet another reluctant oath of loyalty from the aggravated barons. In the summer of 1135, Geoffrey demanded custody of certain key Norman castles as a show of good will from Henry; Henry refused and the pair entered into war. Henry's life ended in this sorry state of affairs - war with his son-in-law and rebellion on the horizon - in December 1135.