Oliver Twist is notable for Dickens' unromantic portrayal of criminals and their sordid lives. The book exposed the cruel treatment of many a waif-child in London, which increased international concern in what is sometimes known as "The Great London Waif Crisis": the large number of orphans in London in the Dickens era. The book's subtitle, The Parish Boy's Progress alludes to Bunyan's The Pilgrim's Progress and also to a pair of popular 18th-century caricature series by William Hogarth, "A Rake's Progress" and "A Harlot's Progress".
An early example of the social novel, the book calls the public's attention to various contemporary evils, including the Poor Law, child labour and the recruitment of children as criminals. Dickens mocks the hypocrisies of his time by surrounding the novel's serious themes with sarcasm and dark humour. The novel may have been inspired by the story of Robert Blincoe, an orphan whose account of hardships as a child labourer in a cotton mill was widely read in the 1830s. It is likely that Dickens's own early youth as a child labourer contributed to the story's development.