Based on an extensive examination of primary sources, the work at hand is the first accurate description of the formation of St. Thomas' Parish, its member churches, its ministers, and others who played a significant part in its colonial history. In the absence of surviving vestry books for St. Thomas' Parish, or even an accurate map of the parish, the author was able to extract valuable information pertaining to St. Thomas' Parish from the surviving vestry books of the neighboring parishes of St. Mark's and St. George's.