He was more interested in literature than music as a child and did not begin to compose until he was fifteen, when he started to teach himself music. In late February or early March 1902 he fathered a child with Marie Scheuchl, a servant girl in the Berg family household. His daughter, Albine, was born on December 4, 1902.
Berg had little formal music education before he became a student of Arnold Schoenberg in October 1904. With Schoenberg he studied counterpoint, music theory, and harmony. By 1906, he was studying music full-time; by 1907, he began composition lessons. His student compositions included five drafts for piano sonatas. He also wrote songs, including his Seven Early Songs (Sieben Frühe Lieder), three of which were Berg's first publicly performed work in a concert that featured the music of Schoenberg's pupils in Vienna that year. The early sonata sketches eventually culminated in Berg's Piano Sonata, Op. 1 (1907–1908); it is one of the most formidable "first" works ever written.
Berg studied with Schoenberg for six years until 1911. Berg admired him as a composer and mentor, and they remained close lifelong friends. Among Schoenberg's teaching was the idea that the unity of a musical composition depends upon all its aspects being derived from a single basic idea; this idea was later known as developing variation. Berg passed this on to his students, one of whom, Theodor Adorno, stated: "The main principle he conveyed was that of variation: everything was supposed to develop out of something else and yet be intrinsically different". The Piano Sonata is an example—the whole composition is derived from the work's opening quartal gesture and its opening phrase.