Every phase of his career and output, the workings of his mind, and his relations with other composers are being studied by scholars in various countries. This collection of articles were written for the Musical Quarterly by internationally known authorities who examine various aspects of Mozart's style, his works, and his life. The introduction is an essay on the special nature of Mozart's genius. Erich Hartzmann leads us into the composer's workshop; Edward E. Lowinsky and Hans T. David analyze his rhythm and harmony; Nathan Broder describes the instrument for which the piano works were written; Ernst Fritz Schmid contrasts Mozart's personality and output with those of his friend and older contemporary, Haydn; Friedrich Blume unravels the tangled skein of the creation of the requiem; Frederick W. Sternfeld establishes the relationship between Papageno's song and Bach's motet Singet dem Herren ein neues lied; Nathan Broder assesses A. E. Muller's Guide to the accurate performance of Mozartean Piano Concertos; and Otto Erich Deutsch investigates the errors and fallacies in Mozart biography.