He was archbishop of Canterbury under Elizabeth I from 1559 and played an important part in the Elizabethan Settlement, helping to reinstate the prayer-book and the Thirty-nine Articles of Religion. In earlier life he was identified with the Reformers at Cambridge, and from 1535 he was chaplain to Anne Boleyn. Parker was an able administrator and a scholar, whose valuable library was bequeathed to Corpus Christi College, Cambridge.