Through work in sports clubs, Hasenclever discovered his love of writing and holding speeches. In 1862/63 he became editor for the democratically oriented newspaper "Westfälische Volkszeitung" in Hagen. As a journalist, he became aware of the writings of the socialist Ferdinand Lassalle, in particular Lasalle's programme for the working class. This became the foundation of the first German social democrat party, with subgroups in most states of the Confederation: the General German Workers' Association ("Allgemeiner Deutscher Arbeiterverein", ADAV), founded on 13 May 1863 in Leipzig and instigated by Lasalle.