Do converts need to be baptized again when they become Catholic?

Converts who have already received a valid Christian Baptism are not baptized again. The Church professes "one Baptism for the forgiveness of sins," because Baptism gives a permanent spiritual character and cannot be repeated (CCC 1272).

What makes a Baptism valid. Baptism requires washing with true water while the minister baptizes in the name of the Father, and of the Son, and of the Holy Spirit, as Christ commanded (Mt 28:19; CCC 1239-1240). The minister must also intend to do what the Church does in Baptism. In an emergency, even a person who is not baptized can baptize validly if these requirements are met (CCC 1256).

Baptisms outside the Catholic Church. Many people baptized in Protestant or Eastern Christian communities are already validly baptized. Their Baptism truly joins them to Christ, even though full communion with the Catholic Church is still lacking (CCC 1271). When they become Catholic, they make a profession of faith and are formally received into full communion. They then ordinarily receive Confirmation and the Eucharist. They are not treated as though their previous Christian life had no value.

When a person does need Baptism. Someone who was never baptized must receive Baptism when entering the Church. Baptism may also be needed when a previous ceremony lacked water, lacked the Trinitarian formula, or was performed without the necessary intention. A ceremony described as a dedication, christening, or naming does not automatically count as Baptism. The parish will usually seek a certificate or reliable testimony and may contact the church where the ceremony occurred.

When the facts are uncertain. The Church investigates carefully rather than simply baptizing everyone again. Canon law states that Baptism, Confirmation, and Holy Orders cannot be repeated when validly received (Canon 845). If serious doubt remains after investigation, the person may receive conditional Baptism, using words that make clear the sacrament is being conferred only if the person is not already baptized (Canon 869).

If you are entering the Church, tell the parish where, when, and how you were baptized. Bring any certificate you have. The pastor or diocese will determine whether the Baptism is recognized, so you do not need to settle the question alone.