The Summa Theologiae or Summa Theologica, often referred to simply as the Summa, is the best-known work of Thomas Aquinas (1225–1274), a scholastic theologian and Doctor of the Church. It is a compendium of all of the main theological teachings of the Catholic Church, intended to be an instructional guide for theology students, including seminarians and the literate laity. Presenting the reasoning for almost all points of Christian theology in the West, topics of the Summa follow the following cycle: God; Creation, Man; Man's purpose; Christ; the Sacraments; and back to God.

Thomas Aquinas was an Italian Dominican friar and priest, an influential philosopher and theologian, and a jurist in the tradition of scholasticism from the county of Aquino in the Kingdom of Sicily.