The Confraternity of Christian Doctrine is an association established in Rome in 1562 for the purpose of providing religious educational program of the Catholic Church, normally designed for children. It is now commonly referred to by its abbreviation, CCD, or simply as "Catechism", and provides religious education to Catholic children attending secular schools. It provides a course of study that has been pre-approved by the diocese as meeting the requirements for children not enrolled in a Catholic school (i.e., public school students) to engage with the sacraments at the same time as their diocese-sponsored peers.

CCD attendance is considered by the Holy See to be vital to children's development as Catholics and an important complement to the limited liturgic participation they regularly experience while accompanying their family to church throughout the year. These classes not only educate children about Jesus and the Catholic faith but more practically prepare children to fully participate in adult spiritual life by providing a secure foundation to receive the sacraments of Penance (confession), the Eucharist (Holy Communion), and Confirmation.

While CCD remains the official shorthand of the institution, occasionally parishes have opted to style their individual program as PSR (Parish School of Religion), SRE (Special Religious Education), and PRP (Parish Religious Program), especially when it occurs as a condensed extended-day summer program. These are merely some examples, and not an exhaustive list.