Music criticism mushroomed in Germany and elsewhere in Europe during Felix Mendelssohn’s lifetime, playing a key role in the transformation of musical ideals and values. While Mendelssohn – unlike his contemporaries Schumann and Wagner – refrained from publishing his views on music, he was well acquainted with the major German, French and English critics of the day and acknowledged the importance of criticism in helping to drive musical reforms. The chapter examines the reasons behind Mendelssohn’s reluctance to write criticism, his attitudes towards different forms of music criticism and his troubled encounters with individual critics, including François-Joseph Fétis and Heinrich Heine. It also explores his relationships with critics who supported him over his career and in some cases helped shape his music, such as Ludwig Rellstab, Adolf Bernhard Marx, Henry Fothergill Chorley, James William Davison, Johann Christian Lobe and Alfred Julius Becher.