Independent Catholicism is a movement comprising clergy and laity who self-identify as Catholic and who form "micro-churches claiming apostolic succession and valid sacraments," despite a lack of affiliation with the main Catholic Church itself. It is virtually impossible to determine the number of jurisdictions, communities, clergy and members who comprise Independent Catholicism,, particularly since the movement "is growing and changing in every moment." Many choose Independent Catholicism as an alternative means to live and express their catholic faith outside the Catholic Church. The structures, beliefs and practices of Independent Catholicism often closely align with those of other Catholic and Christian churches.
Independent Catholicism is part of the larger Independent Sacramental Movement, in which clergy and laity of various faith traditions – including the Eastern Orthodox Church, the Anglican Communion and various non-Catholic Christian churches – have separated themselves from the institutions with which they previously self-identified. Within the Independent Sacramental Movement, various independent churches have sprung from the Eastern Orthodox Church, from which the Catholic Church separated in 1054 A.D., but the members of these independent Orthodox groups most often self-identify as Independent Orthodox, and not as Independent Catholic.
Because the history of Independent Catholicism is closely tied to the birth of the Old Catholic Church in Utrecht, Netherlands, many Independent Catholics mistakenly consider themselves "Old Catholic." In a short, unfavorable characterization of Independent Catholic communities in the U.S., Anglican scholar C.B. Moss warned in 1948: "There are several sects which claim to derive their episcopal succession from Mathew, which are often confused with the Old Catholics, and which in some cases make use of the name 'Old Catholic.' It cannot be too strongly emphasized that none of these sects is Old Catholic or is recognized in any way by the genuine Old Catholic churches in communion with the Archbishop of Utrecht."