Lamb was born in London, the son of Elizabeth Field and John Lamb. Lamb was the youngest child, with a sister 11 years older named Mary and an even older brother named John; there were four others who did not survive infancy. His father John Lamb was a lawyer's clerk and spent most of his professional life as the assistant to a barrister named Samuel Salt, who lived in the Inner Temple in the legal district of London. It was there in Crown Office Row that Charles Lamb was born and spent his youth. Lamb created a portrait of his father in his "Elia on the Old Benchers" under the name Lovel. Lamb's older brother was too much his senior to be a youthful companion to the boy but his sister Mary, being born eleven years before him, was probably his closest playmate. Lamb was also cared for by his paternal aunt Hetty, who seems to have had a particular fondness for him. A number of writings by both Charles and Mary suggest that the conflict between Aunt Hetty and her sister-in-law created a certain degree of tension in the Lamb household. However, Charles speaks fondly of her and her presence in the house seems to have brought a great deal of comfort to him.
Some of Lamb's fondest childhood memories were of time spent with Mrs Field, his maternal grandmother, who was for many years a servant to the Plummer family, who owned a large country house called Blakesware, near Widford, Hertfordshire. After the death of Mrs Plummer, Lamb's grandmother was in sole charge of the large home and, as Mr Plummer was often absent, Charles had free rein of the place during his visits. A picture of these visits can be glimpsed in the Elia essay Blakesmoor in H—shire.
Why, every plank and panel of that house for me had magic in it. The tapestried bed-rooms – tapestry so much better than painting – not adorning merely, but peopling the wainscots – at which childhood ever and anon would steal a look, shifting its coverlid (replaced as quickly) to exercise its tender courage in a momentary eye-encounter with those stern bright visages, staring reciprocally – all Ovid on the walls, in colours vivider than his descriptions.
Little is known about Charles's life before he was seven other than that Mary taught him to read at a very early age and he read voraciously. It is believed that he suffered from smallpox during his early years, which forced him into a long period of convalescence. After this period of recovery Lamb began to take lessons from Mrs Reynolds, a woman who lived in the Temple and is believed to have been the former wife of a lawyer. Mrs Reynolds must have been a sympathetic schoolmistress because Lamb maintained a relationship with her throughout his life and she is known to have attended dinner parties held by Mary and Charles in the 1820s. E. V. Lucas suggests that sometime in 1781 Charles left Mrs Reynolds and began to study at the Academy of William Bird.
His time with William Bird did not last long, however, because by October 1782 Lamb was enrolled in Christ's Hospital, a charity boarding school chartered by King Edward VI in 1553. A thorough record of Christ's Hospital is to be found in several essays by Lamb as well as The Autobiography of Leigh Hunt and the Biographia Literaria of Samuel Taylor Coleridge, with whom Charles developed a friendship that would last for their entire lives. Despite the school's brutality, Lamb got along well there, due in part, perhaps, to the fact that his home was not far distant, thus enabling him, unlike many other boys, to return often to its safety. Years later, in his essay "Christ's Hospital Five and Thirty Years Ago", Lamb described these events, speaking of himself in the third person as "L".
"I remember L. at school; and can well recollect that he had some peculiar advantages, which I and other of his schoolfellows had not. His friends lived in town, and were near at hand; and he had the privilege of going to see them, almost as often as he wished, through some invidious distinction, which was denied to us."
Christ's Hospital was a typical English boarding school and many students later wrote of the terrible violence they suffered there. The upper master (i.e. principal or headteacher) of the school from 1778 to 1799 was Reverend James Boyer, a man renowned for his unpredictable and capricious temper. In one famous story Boyer was said to have knocked one of Leigh Hunt's teeth out by throwing a copy of Homer at him from across the room. Lamb seemed to have escaped much of this brutality, in part because of his amiable personality and in part because Samuel Salt, his father's employer and Lamb's sponsor at the school, was one of the institute's governors.
Charles Lamb suffered from a stutter and this "inconquerable impediment" in his speech deprived him of Grecian status at Christ's Hospital, thus disqualifying him for a clerical career. While Coleridge and other scholarly boys were able to go on to Cambridge, Lamb left school at fourteen and was forced to find a more prosaic career. For a short time he worked in the office of Joseph Paice, a London merchant, and then, for 23 weeks, until 8 February 1792, held a small post in the Examiner's Office of the South Sea House. Its subsequent downfall in a pyramid scheme after Lamb left (the South Sea Bubble) would be contrasted to the company's prosperity in the first Elia essay. On 5 April 1792 he went to work in the Accountant's Office for the British East India Company, the death of his father's employer having ruined the family's fortunes. Charles would continue to work there for 25 years, until his retirement with pension (the "superannuation" he refers to in the title of one essay).
In 1792 while tending to his grandmother, Mary Field, in Hertfordshire, Charles Lamb fell in love with a young woman named Ann Simmons. Although no epistolary record exists of the relationship between the two, Lamb seems to have spent years wooing her. The record of the love exists in several accounts of Lamb's writing. "Rosamund Gray" is a story of a young man named Allen Clare who loves Rosamund Gray but their relationship comes to nothing because of her sudden death. Miss Simmons also appears in several Elia essays under the name "Alice M". The essays "Dream Children", "New Year's Eve", and several others, speak of the many years that Lamb spent pursuing his love that ultimately failed. Miss Simmons eventually went on to marry a silversmith and Lamb called the failure of the affair his "great disappointment".