Born Caroline Reynolds in 1840 in Evansburg, Pennsylvania, she was the daughter of the Rev. John Reynolds who was an English clergyman who had immigrated to the United States in about 1825. She married in 1856, Lt. Adam J. Slemmer, and they lived on military bases in South Carolina, Florida, and Wyoming Territory. He was a Brigadier-General in the Union Army during the American Civil War. Their only child, a son, died young. After Slemmer's death in 1868, she moved to Cambridge, England to visit relatives, including her cousin "Mrs Potts"
In 1874 she married the classicist Richard Claverhouse Jebb. They lived in Glasgow, where her husband was a professor, but spent summers in Cambridge until the death of Benjamin Hall Kennedy vacated the Regius Professor of Greek at Cambridge. Her social circle included Robert Browning, Thomas Carlyle, Charles Darwin, Benjamin Disraeli, George Eliot, Charles Hale, Oliver Wendell Holmes, James Russell Lowell, Alfred Lord Tennyson, Ellen Terry, Mark Twain, and William Thackeray. Her niece, Maud du Puy, daughter of her sister Ellen followed her to England and she took the role of proxy mother, helping to arrange her 1884 marriage to George Darwin, the astronomer son of the naturalist Charles Darwin.
She became Lady Jebb after her husband was knighted in 1900; she was widowed for a second time in 1905. In 1907 she published a biography of her second husband, "Life and letters of Sir Richard Claverhouse Jebb, O. M., LITT. D." with a chapter by Arthur Woollgar Verrall.
In 1918, with difficulties in England due to the First World War, she returned to the United States. She died in Erie, Pennsylvania in 1930.. Her ashes were subsequently interred in the grave of her late husband in the Parish of the Ascension Burial Ground in Cambridge. She is mentioned extensively, well illustrated and characterised as a matriarch in her grand-niece (Maud's daughter) Gwen Raverat's 1952 book Period Piece as "(Great) Aunt Cara", with her husband "(Great) Uncle Dick".
- Gwen Raverat, Period Piece
- Hugh Lloyd-Jones, 'Jebb, Sir Richard Claverhouse (1841–1905)', first published 2004; online edn, May 2006, 2277 words, with portrait illustration
- Life and letters of Sir Richard Claverhouse Jebb, O. M., LITT. D.
- Lady Jebb (Obituaries) The Times Monday, Jul 14, 1930; pg. 14; Issue 45564; col F
- Lady Jebb (Obituaries) "A Cambridge Friend". The Times Thursday, Jul 24, 1930; pg. 14; Issue 45573; col C
- Pennsylvania death records J100 (Soundex index) 
- Mary Reed Bobbitt (1960) With Dearest Love to All The Life and Letters of Lady Jebb