On 16 March 1736 Giovanni Battista Pergolesi died from consumption at age twenty-six in the Franciscan monastery of Pozzuoli near Naples, leaving a considerable number of compositions in all genres: stage works, cantatas, instrumental music and sacred music. On account of the success these compositions had enjoyed in Italy during his life, and the extraordinary fame they achieved in the rest of Europe after his death, a multitude of works bearing his name continued to be disseminated, many of which had little, if any, connection with Pergolesi himself. This phenomenon invites us to question what mechanisms are at work when a piece of music is misattributed, for if spurious or doubtful works can be classified according to their origin, then the identification of recurring patterns may help disentangle similar cases. This essay aims to classify the origins of misattributed sacred works from the first decades of Pergolesi's posthumous reception.