Giovanni Battista Moscaglia was a published composer, solely of secular vocal music, who lived and worked in Renaissance Rome. There is no extant evidence that Moscaglia was a member of the sodality, the Campagnia dei musici di Roma, although he came into contact with its professional members, several of who Moscaglia asked to contribute to a collection of settings of his own poetry. Little is known of his biography, but much is gained from analytical investigation of his music and of his poesia per musica. Moscaglia's six publications of secular music usefully span the two decades of the 1570s and 1580s, a period of significant change in madrigal composition across Italy. The madrigal in Rome at this time has strong characteristics associating it with higher three-voice pieces, such as the villanella and napolitana. It is also known that Roman composers, including Moscaglia, had connections with northern Italian patrons which they pursued through dedications to rulers and by contributions to anthologies associated with academics. While composers could alter their style depending on the destination of a piece, exactly how they incorporated these changes, and what effect it had on their subsequent compositional method is often overlooked. This thesis addresses problems of analytical approach to the late sixteenth-century madrigal, in particular the Roman 'canzonetta-madrigal'. It discusses the musical material of Moscaglia's napolitane and uses this to illuminate his madrigal repertoire. It also offers further examination of the Roman musical environment through a study of Moscaglia in context with his contemporaries, particularly through multi-authored 'canzone' settings to which Moscaglia contributed.