Over the course of the development of the violin and viol families between the second half of the sixteenth century and the first decades of the seventeenth century, players of these instruments did not conform to the existing roles for professional instrumentalists established by wind consorts and other civic musicians. In determining the early sources of professional players of bowed strings, the contexts in which choirboys and young church musicians came to study instrumental music as well as the functions of the ensembles, repertoires, and instruments illuminate the output of the subsequent generations of adult composers and professional musicians, particularly the Venetian School, the first to write idiomatic instrumental music and to specialize in instrumental composition and performance. The acceptance of bowed strings into church music contexts is reflected by the preponderance of string-playing maestri at religious institutions, most notably Marc’Antonio Ingegneri in Cremona and Claudio Monteverdi in Mantua and Venice. The ultimate indication of the presence of string instruments in the church music-educational system and thus the Church as a source of professional string players is the advent of sacred music with designated parts for strings: the stile concertato developed at San Marco and expanded by Gabrieli, Monteverdi, Grandi, and Viadana among others, along with evidence of increasing instrumental participation in the ceremonial sacred music that contributed to its development.