In 1773, Barbauld brought out her first book of poems, after her friends had praised them and convinced her to publish. The collection, entitled simply Poems, went through four editions in just one year and surprised Barbauld by its success. Barbauld became a respected literary figure in England on the reputation of Poems alone. The same year she and her brother, John Aikin, jointly published Miscellaneous Pieces in Prose, which was also well-received. The essays in it (most of which were by Barbauld) were favourably compared to Samuel Johnson's.
In May 1774, despite some "misgivings", Barbauld married Rochemont Barbauld (1749–1808), the grandson of a French Huguenot and a former pupil at Warrington. According to Barbauld's niece, Lucy Aikin:
[H]er attachment to Mr. Barbauld was the illusion of a romantic fancy—not of a tender heart. Had her true affections been early called forth by a more genial home atmosphere, she would never have allowed herself to be caught by crazy demonstrations of amorous rapture, set off with theatrical French manners, or have conceived of such exaggerated passion as a safe foundation on which to raise the sober structure of domestic happiness. My father ascribed that ill-starred union in great part to the baleful influence of [Jean-Jacques Rousseau's] 'Nouvelle Heloise,' Mr. B. impersonating St. Preux. [Barbauld] was informed by a true friend that he had experienced one attack of insanity, and was urged to break off the engagement on that account.—'Then' answered she, 'if I were now to disappoint him, he would certainly go mad.' To this there could be no reply; and with a kind of desperate generosity she rushed upon her melancholy destiny.
After the wedding, the couple moved to Suffolk, near where Rochemont had been offered a congregation and a school for boys. Barbauld took this time and rewrote some of the psalms, a common pastime in the 18th century, publishing them as Devotional Pieces Compiled from the Psalms and the Book of Job. Attached to this work is her essay "Thoughts on the Devotional Taste, on Sects and on Establishments", which explains her theory of religious feeling and the problems inherent in the institutionalisation of religion.
It seems that Barbauld and her husband were concerned that they would never have a child of their own and in 1775, after only a year of marriage, Barbauld suggested to her brother that they adopt one of his children:
I am sensible it is not a small thing we ask; nor can it be easy for a parent to part with a child. This I would say, from a number, one may more easily be spared. Though it makes a very material difference in happiness whether a person has children or no children, it makes, I apprehend, little or none whether he has three, or four; five, or six; because four or five are enow [sic] to exercise all his whole stock of care and affection. We should gain, but you would not lose.
Eventually her brother conceded and the couple adopted Charles; it was for him that Barbauld wrote her most famous books: Lessons for Children (1778–79) and Hymns in Prose for Children (1781).