Although best-known to record collectors as the tenor soloist on the first recording of Mahler's Das Lied von der Erde, Kullman had a wide-ranging career, beginning with substantial successes in Europe before settling into a quarter century of dependable performances at the Metropolitan Opera. Essentially a lyric singer, Kullman undertook weightier roles in the final stages of his time before the public. Born Charles Kullmann (he changed the spelling of his last name in the late '40s), the singer began performing in church choirs at age eight. He attended Yale University, graduating in 1924 after preparing to train as a medical doctor. Financial difficulties interfered, however, and he fell back upon his avocation. His having been a member of the Yale Glee Club and having won first prize in an intercollegiate singing contest during his senior year led him to believe he could succeed in making music a career. After working with a voice teacher in New Haven who shifted his vocal placement from lyric baritone to tenor, Kullman auditioned at the Juilliard School of Music and won a scholarship. Upon completing three years of study, Kullman won another scholarship, this one affording him the opportunity to study at the American University in Fontainebleau. In 1928, Kullman returned to America to teach voice at Smith College, where he also appeared in several school opera productions. Invited to join tenor Vladimir Rozing's American Opera Company, Kullman left Smith College and began singing leading roles with Rozing's ensemble. Two years after his return to the United States, Kullman was back in Europe to coach the operatic repertory. When an associate brought his name to the attention of conductor Otto Klemperer, an audition was arranged and Kullman was hired for the innovative Kroll Theater. The American tenor made a successful debut on February 24, 1931, as Pinkerton in Madama Butterfly. A year later, Kullman's growing reputation led to his engagement by the Berlin Staatsoper, where he became a favorite with the public. Demand obliged the company to present him often in Madama Butterfly, an opera previously heard there only occasionally. During his time there, the tenor worked with Germany's leading conductors, including Wilhelm Furtwängler, Erich Kleiber, and Leo Blech. In 1934, Kullman made his debut with the Vienna Staatsoper, followed by his first appearance at London's Covent Garden. The opera was the rarely heard Schwanda and critics were warmly appreciative of Kullman's performance. Beginning in 1934, Kullman was engaged for the Salzburg Festival, winning further accolades for his performances. In 1935, his Florestan with Arturo Toscanini was a triumph and his Walther in the festival's 1936 production of Die Meistersinger, also led by Toscanini, prompted critic Richard Cappell to praise his singing as "charmingly fresh, musical, lyric, unforced." As Kullman's European career continued unabated, Metropolitan Opera general manager Edward Johnson offered a contract to the tenor. For his December 20, 1935, Metropolitan debut as Gounod's Faust, supporters by the trainload traveled from New Haven to hear their native son. Critics that night heard the qualities that allowed the tenor to sing a widely varied repertory at the house over the next 25 years, notably an unforced freshness and authority. Kullman was nearly as active on the concert stage as in the opera house, appearing often with the most celebrated conductors. An active radio broadcasting career also attested to his popularity.