An accomplished musician, having studied music to degree level, he took a leading part in the revision and updating of hymnals widely used within Anglicanism, chairing the board of the publisher Hymns Ancient & Modern Ltd. for 20 years.

[5][6] Although he did not show much aptitude as a Grecian, his lifelong love of music made its first appearance and resulted in his receiving organ lessons from Henry Ley.

[2][7] A highlight of his undergraduate musical career was playing a two piano arrangement of Chabrier's España with Boris Ord, then organist of King's College, Cambridge.

His rising academic reputation was confirmed in 1953 with the publication of a project which had occupied him since the days of his curacy—his new translation of Origen's Contra Celsum, with introduction and notes.

[12] Chadwick moved to Oxford in 1959, to take up the position of Regius Professor of Divinity (and with it the associated canonry at Christ Church Cathedral)[13][14] at the relatively young age of 39.

[20] In the 1960s, along with scholars like E. R. Dodds, Peter Brown, and John Matthews, Chadwick helped make Oxford a centre in the developing study of Late Antiquity.

He clarified the classical philosophical roots of Christian thinkers from Justin Martyr and Clement of Alexandria to Augustine of Hippo,[9] and set about raising academic standards within the theology department—in particular making the degree of Doctor of Divinity (DD) into a genuine research degree, as opposed to an honorary award made to senior clerics who had produced a volume of sermons.

[2][7] He was disappointed that he was allowed to include so few footnotes in the original publication, and correspondingly delighted when the publishers of a German edition requested additional notes for their translation.

The report ultimately led to changes in the doctrinal affirmations required of Church of England clergy at their ordination or on taking up new appointments.

[3][22] This period was not entirely happy; a scholarly ability to see all sides of a question, along with an ingrained desire not to upset his colleagues, sometimes made it hard for him to make a quick or firm decision.

The new organist, Simon Preston, had ambitious plans for improving musical standards, and Chadwick was pleased to be able to support these, not least by raising funds for a new organ.

[9][24][25] He was a master of the Anglican approach of producing statements capable of a range of interpretations to enable common ground to be reached; this worked well for simpler historical differences, but did not always impress the Roman Catholic members of the commission when it came to questions of ecclesiology and church authority.

[2] He was also able to use his historical background to put forward summaries of early church positions on a variety of subjects, and he had a true desire to establish consensus on the basis of the principles revealed by this research.

[2][5][9] After four years in retirement, he received an unexpected invitation to become Master of Peterhouse in 1987, thus becoming the first person in over four centuries to lead a college at both Oxford and Cambridge.

The college had been experiencing some problems following the admission of the first female students, to which some fellows were implacably opposed, making their displeasure known at High Table.

[7] A capable preacher, though doubtful of his ability when preaching to a non-academic congregation, Chadwick was well regarded as a lecturer and companion at High Table.

[33] He also treasured a stole given to him by Pope John Paul II in 1982, and this was placed on his coffin during his funeral at Christ Church on 25 June 2008.

[36] Chadwick's love of music led him to serve for twenty years as chairman of the council of Hymns Ancient & Modern Ltd. During this time the company expanded its scope.