Principal viola of Osesp since 1998, Horácio Schaefer began his musical education in São Paulo and completed his studies with Max Rostal in Germany. While there, he became a member of the Deutsche Bachsolisten chamber orchestra, performed with the Frankfurt Radio Symphony, and was appointed principal viola of the Essen Philharmonic.
He has taught in the music department of São Paulo University and at the School of Music and Fine Arts of the State of Paraná (Curitiba). Between 1995 and 1998 he was principal viola of the orchestra of the Municipal Theatre in São Paulo.