Each year on Holy Saturday during the Easter Vigil, thousands are baptized into the Catholic Church in the United States. Parishes welcome these new Catholics through the Order of Christian Initiation of Adults.

Reception into the full communion of the Catholic Church describes the process for entrance into the Catholic Church for already baptized Christians. In most cases, these individuals make a profession of faith but are not baptized again.

Catholics who were baptized as infants but did not receive catechesis receive Confirmation and/or the Eucharist after participation in a period of formation. This process of formation is completed with the reception of the Sacraments of Confirmation and the Eucharist, often at the Easter Vigil or during the Easter Season.

Christian Initiation of Adults, USCCB

OCIA is primarily a weekly class that runs from October to Easter Saturday.

Holy Baptism is the basis of the whole Christian life, the gateway to life in the Spirit (vitae spiritualis ianua), and the door which gives access to the other sacraments. Through Baptism we are freed from sin and reborn as sons of God; we become members of Christ, are incorporated into the Church and made sharers in her mission: "Baptism is the sacrament of regeneration through water in the word."

Catechism of the Catholic Church 1213

By the sacrament of Confirmation, [the baptized] are more perfectly bound to the Church and are enriched with a special strength of the Holy Spirit. Hence they are, as true witnesses of Christ, more strictly obliged to spread and defend the faith by word and deed.

Catechism of the Catholic Church 1285

Confirmation is a two-year program. The first year involves at-home formation. The second year has a weekly class. 

The matrimonial covenant, by which a man and a woman establish between themselves a partnership of the whole of life, is by its nature ordered toward the good of the spouses and the procreation and education of offspring; this covenant between baptized persons has been raised by Christ the Lord to the dignity of a sacrament.

Catechism of the Catholic Church 1601