There is very little direct evidence about Grosseteste's education. He may have received a liberal arts education at Hereford, in light of his connection with the Bishop of Hereford William de Vere in the 1190s and a recommendation from Gerald of Wales. It is fairly certain that Grosseteste was a master by 1192, but whether that indicated that he had completed a course of studies is unclear. Grosseteste acquired a position in the bishop's household, but at the death of this patron he disappears from the historical record for several years. He appears again in the early thirteenth century as a judge-delegate in Hereford, but there are no surviving details of where he resided or whether he had continued to study.
By 1225, he had gained the benefice of Abbotsley in the diocese of Lincoln, by which time he was a deacon. On that period in his life, scholarship is divided. Some historians argue that he began his teaching career in theology at Oxford in this year, whereas others have more recently argued that he used the income of his ecclesiastical post to support studies in theology at the University of Paris. However, there is clear evidence that by 1229/30 he was teaching at Oxford, but on the periphery as the lector in theology to the Franciscans, who had established a convent in Oxford about 1224. He remained in this post until March 1235.
Grosseteste may also have been appointed Chancellor of the University of Oxford. However, the evidence for this comes from a late thirteenth century anecdote whose main claim is that Grosseteste was in fact entitled the master of students (magister scholarium).
At the same time he began lecturing in theology at Oxford, Hugh of Wells, Bishop of Lincoln, appointed him as Archdeacon of Leicester, and he also gained a prebend that made him a canon in Lincoln Cathedral. However, after a severe illness in 1232, he resigned all his benefices (Abbotsley and Leicester), but retained his prebend. His reasons were due to changing attitudes about the plurality of benefices (holding more than one ecclesiastical position simultaneously), and after seeking advice from the papal court, he tendered his resignations. The angry response of his friends and colleagues to his resignations took him by surprise and he complained to his sister and to his closest friend, the Franciscan Adam Marsh, that his intentions had been completely misunderstood.
As a master of the sacred page (manuscripts of theology in Latin), Grosseteste trained the Franciscans in the standard curriculum of university theology. The Franciscan Roger Bacon was his most famous disciple, and acquired an interest in the scientific method from him. Grosseteste lectured on the Psalter, the Pauline epistles, Genesis (at least the creation account), and possibly on Isaiah, Daniel and Sirach. He also led disputations on such subjects as the theological nature of truth and the efficacy of the Mosaic Law. Grosseteste also preached at the university and appears to have been called to preach within the diocese as well. He collected some of those sermons, along with some short notes and reflections, not long after he left Oxford; this is now known as his Dicta. His theological writings reveal a continual interest in the natural world as a major resource for theological reflection and an ability to read Greek sources (if he ever learned Hebrew, it would be not until he became bishop of Lincoln). His theological index (tabula distinctionum) reveals the breadth of his learning and his desire to communicate it in a systematic manner. However, Grosseteste's own style was far more unstructured than many of his scholastic contemporaries, and his writings reverberate with his own personal views and outlooks.