Exploring many aspects of Felix Mendelssohn’s multi-faceted career as musician and how it intersects with his work as composer, contributors discuss practical issues of music making such as performance space, instruments, tempo markings, dynamics, phrasings, articulations, fingerings, and instrument techniques. They present the conceptual and ideological underpinnings of Mendelssohn’s approach to performance, interpretation, and composing through the contextualization of specific performance events and through the theoretic actualization of performances of specific works. Contributors rely on manuscripts, marked or edited scores, and performance parts to convey a deeper understanding of musical expression in 19th-century Germany. This study of Mendelssohn’s work as conductor, pianist, organist, violist, accompanist, music director, and editor of old and new music offers valuable perspectives on 19th-century performance practice issues.