The Rite of Christian Initiation of Adults (RCIA) is the typical way adults come into the Church. For those who have not been baptized in another Christian church, this process is meant to form them into the fullness of the Christian life and to become disciples of Jesus, their teacher. This includes an initiation into the mystery of salvation, the practice of faith, hope, and love, and other virtues in a succession of liturgical rites. Those baptized into another Christian church and now seeking full communion with the Catholic Church are also welcomed to participate along with catechumens in the RCIA in the process of learning about the Catholic faith and being formed in that faith. For a baptized Christian, reception into full communion with the Catholic Church involves reception of the Sacrament of Penance and Reconciliation and then a Profession of Faith followed by the celebration of Confirmation and the Eucharist.

In the Diocese of Birmingham, the Offices of Sacred Liturgy and Religious Education share in the task of assisting parishes in their own RCIA processes. The offices are aided in this by a Subcommittee on Christian Initiation made up of representatives from the diocese.