Jill de Villiers has authored and edited four books about language acquisition and numerous chapters and journal articles, most of them on the acquisition of complex syntax in preschoolers. She is now studying the impact of language acquisition on cognitive development, particularly on theory of mind. In addition to the development of new diagnostic tests for language assessment, she consults on designing computer software for language intervention.

De Villiers received her bachelor's in psychology from Reading University in England in 1969 and then a doctorate in experimental psychology from Harvard University in 1974, where she worked on language acquisition. She then taught at Harvard as an assistant professor of psychology from 1974 to 1979. In 1979 she took a position jointly in the psychology and philosophy departments at Smith College, where she is now the Sophia and Austin Smith Professor.

In her free time, de Villiers is a consumer of contemporary novels. Her interests came together in a novel in 2017, The Larcher, which she wrote with a friend, in which the child protagonist develops a false belief based on a linguistic misinterpretation. In 2018, she tried her hand at an academic novel, the humorous novels of that genre having entertained her for years. But it was mostly men who wrote them. A Hundred Stones has a woman professor as the protagonist. Both novels were written under the pen name of J.J. Amies. She narrated them as audiobooks in 2019. In 2020, a collaboration with the artist Salem Sloane resulted in her first children’s picture book, Thank you, Dr. Ophelia! meant as a rich (and funny) narrative about the mind, and mistaken beliefs.