The purpose of this study is to make Ignacio de Jerusalem's Los Maitines de Nuestra Senora de la Concepcion (The Matins for Our Lady of the Conception), composed in 1768 for the Mexico City Cathedral, accessible to modern choral and orchestral ensembles through the creation of a historically informed edition of the work that incorporates the latest scholarship on editorial and performing practices of the Mexican Baroque. Jerusalem's manuscript is housed in the Mexico City Cathedral archive and on microfilm in the Biblioteca Nacional de Antropologia e Historia of Mexico, D.F. The Matins has not been performed since the nineteenth century, and never outside of Mexico, nor has it been the subject of scholarly research. Set for choir and chamber orchestra with arias, recitatives, and choral movements, the work represents the most elaborate of Jerusalem's compositions. This document provides background information and a discussion of performance practice and editorial protocol based on research and the performance of the Invitatory and First Nocturn of The Matins by the University of Arizona Collegium Musicum. The document culminates with a performance edition of the Invitatory and First Nocturn of Los Maitines de Nuestra Senora de la Concepcion.