Koen Kaptijn is a highly acclaimed trombonist, composer and performer and has operated at the forefront of the contemporary music performance scene in the Netherlands for the last 25 years. He was actively involved in premieres of more than 600 pieces. 
Koen is a member of Asko|Schönberg, 7090, New Trombone Collective, Rosa Ensemble, New European Ensemble and Nieuw Amsterdams Peil. 
In the past he has been a member of Orchestra De Volharding, Maarten Altena Ensemble, Nieuw Ensemble, Class Ensemble, David Kweksilber Bigband and Splendor Amsterdam and worked as a freelancer with Nederlands Blazers Ensemble, Corrie van Binsbergen, Orkater, Internationaal Toneel Amsterdam, LOD Gent, Theater Transparant Antwerpen and Klangforum Wien.

Besides his work as a musician, he also composes pieces for his own ensembles and works as a composer/sound designer for theatre.