Harriet began publishing her works when she was pregnant with her third child, Helen (who also went on to be a campaigner for women's rights, particularly regarding education and the vote). She provided a variety of literature for the Unitarian journal "Monthly Repository" and the Society for the Distribution of Useful Knowledge. Though she made many contributions over the years, little of her own work was published under her own name during her lifetime. She was the co-author of several newspaper articles on domestic violence published anonymously in the "Morning Chronicle", "Daily News", and "Sunday Times" in the 1840s. She read and commented on all the material produced by John Stuart Mill, who called her a valuable contributor to much of his work, especially "On Liberty", which he later dedicated to her when it was published in 1859, a year after her death. She also contributed to "Principles of Political Economy".