Stephen stayed in Cincinnati from the Fall of 1846 until January or early February, 1850. These were the years of the Mexican War, and Dunning enlisted in the Army and left Stephen in the office with his partner in the business, Archibald Irwin. Stephen was a good bookkeeper; there is no evidence to support the legends that he was an idler and he spent much of his spare time cultivating the acquaintance of minstrel performers who might sing his songs in public. Some of these singers were unscrupulous and took the manuscript copies to publishers who promptly issued pirated editions. When Stephen himself found a publish to issue Oh! Susanna and Old Uncle Ned, several other firms had already published these songs.

Oh! Susanna was probably composed before Stephen went to Cincinnati, but it was while he was there that he came in touch with W.C. Peters, a music publisher Stephen's family had known in Pittsburg. Stephen gave Peters a number of songs, either for $100, or as an outright present, we do not know which. Peters made a fortune from them and Foster had no royalty interest. Instead, he gained from the songs the fame he needed to establish himself as a song-writer. Oh! Susanna became a folk song almost overnight. The Forty-niners caught it up and sang it on their way to California, and there was hardly a minstrel troupe that did not sing it at every performance.

As a result of this success, two publishers, one in New York and the other in Baltimore, offered Stephen royalty contracts and agreed to pay him two cents for every copy of his songs they sold. Now he could return to his family in Allegheny and prove to them that he could make a better living by song-writing than as a bookkeeper. He could so propose marriage to Jane McDowell and tell her that he had good prospects for supporting her. Jane was the daughter of a Pittsburg physician who had died the previous Spring. She and Stephen were married July 22, 1850, and after a brief honeymoon in New York and Baltimore, they went to live with the Foster family in Allegheny.

Nobody knows exactly how happy a marriage it proved to be, even though the marital relations of Stephen and Jane have been used as the basis of fanciful movie plots and for radio sketches. Probably it was as happy as could be expected with a man of Stephen's temperament. Although there were several separations, one of them in 1854, it is not clear that they were caused by estrangements, and certainly not because Stephen loved another woman. In Stephen's last years Jane left him because he could support her. Perhaps Jane was not overfond of music and had a lukewarm interest in Stephen's song-writing. It is probably that she nagged him, and that Stephen resented her trying to make him more of a businessman. Stephen was a dreamer, improvident and temperamentally difficult. Yet he was generous, sociable and lovable. He undoubtedly loved his wife and he adored his little daughter, Marion. In her old age this only child of Stephen Foster remembered her father chiefly for his constant desire that she and her mother should have a good time.