Beach followed this up with an important milestone in music history: her Gaelic Symphony, the first symphony composed and published by an American woman. It premiered October 30, 1896, performed by the Boston Symphony "with exceptional success," although "whatever the merits or defects of the symphony were thought to be, critics went to extraordinary lengths in their attempts to relate them to the composer's sex." Composer George Whitefield Chadwick (1854–1931) wrote to Beach that he and his colleague Horatio Parker (1863–1919) had attended the Gaelic Symphony's premiere and much enjoyed it: "I always feel a thrill of pride myself whenever I hear a fine work by any of us, and as such you will have to be counted in, whether you it or not – one of the boys." These "boys" were a group of composers unofficially known as the Second New England School, and included not only Chadwick and Parker but also John Knowles Paine (1839–1926), Arthur Foote (1853–1937), and Edward MacDowell (1860–1908). With the addition of Beach, they collectively became known as the Boston Six, of whom Beach was the youngest.