Elizabeth Cavendish was encouraged in her literary interests from a young age by her father, William Cavendish, 1st Duke of Newcastle, himself an author and patron of the arts surrounded by a literary coterie which included Ben Jonson, Thomas Shadwell, and John Dryden.

Her mother, Elizabeth Bassett, died in 1643, and her father was later remarried to noted writer Margaret Cavendish.

William Cavendish and his sons relocated to France during the English Civil War, while Egerton and her sisters Jane and Frances remained at the besieged family seat in Nottinghamshire until 1645 when she relocated to her husband's home where she was relatively sheltered from the rest of the war.

"[2] Egerton's final manuscript collection, known as the "Loose Papers," is made up of prayers, meditations, and essays, some written in response to the illness and death of her children — only four of whom survived to adulthood — and some to pregnancy and childbirth: O Lord, I knowe thou mightest have smothered this my Babe in the wombe, but thou art ever mercyfull, and hast at this time brought us both from greate dangers, and me from the greate torture of childbirth.

Her essays on marriage and widowhood "open a highly unusual window on the thinking of a seventeenth-century woman.