Italian composer and theorist. A pupil of Willaert in Venice, he was court music director and teacher at Ferrara before 1539, and then joined the retinue of Cardinal Ippolito d'Este in Rome. His first book of 5-voice madrigals appeared in Venice in 1546, and he subsequently followed the cardinal to Rome. In 1551 he engaged in a famous debate with the Portuguese musician Vicente Lusitano concerning the ancient Greek genera (diatonic, chromatic, and enharmonic); he lost the debate, but expanded his ideas in his treatise L'antica musica ridotta alla moderna prattica(Rome, 1555), which gives Pythagorean harmonics derived from Boethius and addresses solmization, modes, and counterpoint in the three genera. By 1561 Vicentino had constructed both an archicembalo, and archiorgano, keyboard instruments capable of playing chromatic and enharmonic genera. Around 1563 he left the service of the cardinal to become maestro di cappella at Vicenza Cathedral; later he was in Milan. He is chiefly known today for the advanced theories in his L'antica musica ridotta alla moderna prattica (1555) on supposedly Greek enharmonic music; he divided the whole tone into five parts, devising an instrument called the archicembalo with a 31-note octave capable of distinguishing F sharp from G flat, for example. His madrigals exploit these microtones. The musical establishment opposed his ideas, though he was asked by the progressive fathers of the Council of Trent to write a 'chromatic' Mass as a sample of liturgically acceptable polyphony.