When the practice of casting mature actresses to play the roles of coy, youthful heroines began to wane in the mid-1850s, the charming ingénue Mrs. J. H. Allen emerged to claim such roles. Performing exclusively under her married name (she was the wife of actor and theater manager J. H. Allen), Mrs. Allen made her New York acting debut in 1855. Three years later, the New York Times hailed her as "the most beautiful woman on the New-York stage" and noted her rapid rise to "a prominent position as the leading actress" at Wallack's, the city's premier theater. In 1859, Allen played Zoe, the tragic mixed-race heroine, in Dion Boucicault's stirring new melodrama The Octoroon before joining Laura Keene's company for the following theatrical season. It was during her association with Keene that Allen appeared as the flag-draped Columbia in the wildly popular extravaganza The Seven Sisters, which ran for 253 performances.