Previously, they had studied at the Mozarteum in Salzburg, the Music Academies (Muskhoschschule) of both Basle, Switzerland and Hanover, Germany, and the University of Cincinnati. Their main teachers were Hatto Beyerle, Heinrich Schiff, and Walter Levin, and at Cincinnati they studied with the LaSalle Quartet.
They had an opportunity to meet the important early music specialist Nikolaus Harnoncourt, who interested then in earlier repertory, and with Latvian violinist Gidon Kremer, one of the world's leading exponents of newer music and unusual repertory. This resulted in the Hagen String Quartet's breadth of repertory, which extends from before Bach to the latest works of Witold Lutoslawski and György Ligeti.
Kremer invited the Hagens to participate in the Lockenhaus Chamber Music Festival where, in 1981, they won both the Jury Prize and the Audience Prize. In 1982 they won first prize at the Portsmouth String Quartet Competition. A part of this prize was a debut at London's prime chamber music and recital venue Wigmore Hall, which was a great success.
The quartet continued winning prizes, taking firsts at Evian, Bordeaux, and Banff. Soon their hometown invited them to perform at the Salzburg Festival and they became part of the busy musical scene in the city, participating regularly in the Festival, the Mozart-Week celebrations, and in regular concert series held in Salzburg. They also continue as regular participants in the Lockenhaus Chamber Music Festivals.
The Hagen String Quartet became an exclusive act with Deutsche Grammophon, which has issued a series of recordings of their performances at Lockenhaus as well as a many others.
The Quartet often performs with leading artists of the day, including pianists Paul Gulda and Oleg Maisenberg, violist Gerard Causée, and their teacher cellist Heinrich Schiff.
Angelika Hagen has retired from the quartet and been replaced as second violinist by Rainer Schmidt.