In 1730, Flemish Bishop Jean Baptiste Ludovico de Castillion (1680-1753) produced a collection of French-style guitar music entitled Recueil des pieces de guitarre composées par Mr. François Le Cocq (B-Bc MS S 5615). Significantly, this text (alongside an abridged copy of the manuscript by Castillion) is the largest surviving source of compositions formally attributed to François Le Cocq (fl. 1685-1729) who was guitarist at the Chapel Royal in Brussels. This project investigates Castillion’s manuscript of 1730. Specifically, compositions of François Le Cocq are examined to appraise practical implications for performance on the 5-couse guitar. Music by Le Cocq and his contemporaries is considered to evaluate stylistic trends of late seventeenth-century French-style guitar composition. Through this research and practical testing, ambiguities evident in Castillion’s manuscript are evaluated, leading to an informed interpretation of François le Cocq’s music for the 5-course guitar.