Charlotte Forten's grandfather, James, amassed a fortune in sail making, becoming one of the wealthiest blacks residents of Philadelphia. He and his wife hosted leading black and white abolitionists regularly. Charlotte's parents Robert and Mary continued the activism as did her uncles and aunts, who helped found a the Philadelphia Female Anti-Slavery Society, which drew membership from black and white abolitionist circles. Through her family Charlotte became an outspoken abolitionist, famous in her own right. She developed a passion for writing poems, many of which focused on anti-slavery.
The Forten family had a long association with the abolitionist side of the Grimke family, and in 1878 Charlotte married Francis James Grimke who had been born a slave. After gaining his freedom Francis entered Princeton Theological Seminary.
Charlotte Forten Grimke was the niece of Harriet Purvis who was a regular visitor to Staten Island and was close friends of the Shaw family (see her journal entry below). She was a regular visitor to Staten Island, which she described as "particularly beautiful." (See journal entry below).