In 1971 von Beust became member of the conservative Christian Democratic Union (CDU). In 1973, after finishing high school, he worked for the CDU group in Hamburg's city-state parliament ("Bürgerschaft"), a position he held until he started to study law in 1975 at the University of Hamburg. From 1977 until 1983 he was Hamburg president of the youth organisation of his party. Since 1978 Beust has been a member of the Hamburg city-state's parliament. In 1983 he successfully completed his studies and became an independent lawyer.