Her main area of research is early modern women's philosophy. She is the author of The Philosophy of Mary Astell (OUP, 2015) and Women Philosophers of the Seventeenth Century (CUP, 2002), and co-author with Karen Green of A History of Women's Political Thought in Europe, 1400-1700 (CUP, 2009). She recently published a modern edition of Mary Astell's Christian Religion, as Professed by a Daughter of the Church of England (CRRS and Iter, 2013)