William Coleman performs regularly as a chamber musician and soloist and is a violist in the renowned Berlin Kuss Quartet. He gave concerts at the Salzburg Festival and the Edinburgh Festival, in the Berlin Philharmonie, in the Vienna Konzerthaus, in London's Wigmore Hall, in the Théâtre du Châtelet in Paris, in the Library of Congress in Washington and in New York's Carnegie Hall. His chamber music partners include Pierre-Laurent Aimard, Yuri Bashmet, Miklos Perenyi, Kim Kashkashian, Boris Pergamenschikov, Leif Ove Andsnes, Till Fellner and Antje Weithaas. He is a regular at the International Musicians' Seminar Prussia Cove, and in summer 2020 he will take part in the famous Marlboro Festival in Vermont (USA). He gave master classes at the universities of Berlin and Hamburg as well as in the USA, at the Kronberg Academy and at the Suntory Academy Tokyo. In 2020, the complete cycle of Beethoven quartets will be released live from Suntory Hall Tokyo, played on the famous "Paganini Quartet" instruments by Antonio Stradivarius, on loan from the Nippon Music Foundation. In 2018 the quartet won an Opus Klassik prize. In April 2019, Coleman replaced Yuri Bashmet as a jury member at the Tertis International Viola Competition on the Isle of Man. In 2021 he was a jury member of the Tokyo International Viola Competition.