The Reverend John Keble, who would become one of the leaders of the Oxford Movement, stood as godfather to Matthew. "Thomas Arnold admired Keble's 'hymns' in The Christian Year, only reversing himself with exasperation when this old friend became a Romeward-tending 'High Church' reactionary in the 1830s." In 1828, Arnold's father was appointed Headmaster of Rugby School and his young family took up residence, that year, in the Headmaster's house. In 1831, Arnold was tutored by his uncle, Rev. John Buckland in the small village of Laleham. In 1834, the Arnolds occupied a holiday home, Fox How, in the Lake District. William Wordsworth was a neighbour and close friend. In 1836, Arnold was sent to Winchester College, but in 1837 he returned to Rugby School where he was enrolled in the fifth form. He moved to the sixth form in 1838 and thus came under the direct tutelage of his father. He wrote verse for the manuscript Fox How Magazine co-produced with his brother Tom for the family's enjoyment from 1838 to 1843. During his years there, he won school prizes for English essay writing, and Latin and English poetry. His prize poem, "Alaric at Rome," was printed at Rugby.
In 1841, he won an open scholarship to Balliol College, Oxford. During his residence at Oxford, his friendship ripened with Arthur Hugh Clough, another Rugby old boy who had been one of his father's favourites. Arnold attended John Henry Newman's sermons at St. Mary's but did not join the Oxford Movement. His father died suddenly of heart disease in 1842, and Fox How became his family's permanent residence. Arnold's poem Cromwell won the 1843 Newdigate prize. He graduated in the following year with a 2nd class honours degree in Literae Humaniores (colloquially Greats).
In 1845, after a short interlude of teaching at Rugby, he was elected Fellow of Oriel College, Oxford. In 1847, he became Private Secretary to Lord Lansdowne, Lord President of the Council. In 1849, he published his first book of poetry, The Strayed Reveller. In 1850 Wordsworth died; Arnold published his "Memorial Verses" on the older poet in Fraser's Magazine.
Wishing to marry, but unable to support a family on the wages of a private secretary, Arnold sought the position of, and was appointed, in April 1851, one of Her Majesty's Inspector of Schools. Two months later, he married Frances Lucy, daughter of Sir William Wightman, Justice of the Queen's Bench. The Arnolds had six children: Thomas (1852–1868); Trevenen William (1853–1872); Richard Penrose (1855–1908), an inspector of factories; Lucy Charlotte (1858–1934) who married Frederick W. Whitridge of New York, whom she had met during Arnold's American lecture tour; Eleanore Mary Caroline (1861–1936) married (1) Hon. Armine Wodehouse (MP) in 1889, (2) William Mansfield, 1st Viscount Sandhurst, in 1909; Basil Francis (1866–1868).
Arnold often described his duties as a school inspector as "drudgery," although "at other times he acknowledged the benefit of regular work." The inspectorship required him, at least at first, to travel constantly and across much of England. "Initially, Arnold was responsible for inspecting Nonconformist schools across a broad swath of central England. He spent many dreary hours during the 1850s in railway waiting-rooms and small-town hotels, and longer hours still in listening to children reciting their lessons and parents reciting their grievances. But that also meant that he, among the first generation of the railway age, travelled across more of England than any man of letters had ever done. Although his duties were later confined to a smaller area, Arnold knew the society of provincial England better than most of the metropolitan authors and politicians of the day."