After a four-year courtship, Kelley married fellow abolitionist Stephen Symonds Foster in 1845. In 1847, she and her husband purchased a farm in the Tatnuck region of Worcester, Massachusetts and named it "Liberty Farm". She gave birth to their only daughter in 1847. The farm served both as a stop on the Underground railroad and as a refuge for fellow reformers. Kelley continued her efforts as a lecturer and fundraiser throughout the North until 1850, when declining health forced her to reduce traveling. She carried on an active correspondence and local meetings to work for the cause.
