We have two distinct Baptismal practices. The oldest one is the case of adults who realize their need for God, seek Baptism, and experience the forgiveness of sins in the waters of Baptism. This form of Baptism was practiced by the Apostles and the first evangelists when the Church's preaching ministry began after Pentecost. This form of Baptism was the only form practiced for the first few centuries of the Church's life. It is still done for adults, and school-aged children, who seek Church membership.
All Catholic churches offer instruction for adults who wish to be baptized.
These instructions are called the Rite of Christian Initiation for Adults. It is a process of faith formation which lasts from six to nine months, culminating at the Easter Vigil. The new initiates are Baptized, Confirmed and given Eucharist during the Vigil Liturgy. The second form of baptismal practice is the baptism of infants. This practice developed in the fourth and fifth centuries as a response to the desires of Christian parents that their children not grow up without the benefit of the saving Grace of Christ.