Act of Contrition
Traditional Version
O my God, I am heartily sorry for having offended Thee, and I detest all my sins because of Thy just punishments, but most of all because they offend Thee, my God, Who art all good and deserving of all my love.
I firmly resolve, with the help of Thy grace, to sin no more and to avoid the near occasions of sin. Amen.
A Simpler Version
My God, I am sorry for my sins with all my heart. In choosing to do wrong and failing to do good, I have sinned against You, whom I should love above all things.
I firmly intend, with Your help, to do penance, to sin no more, and to avoid whatever leads me to sin. Our Savior Jesus Christ suffered and died for us. In His name, my God, have mercy. Amen.
Latin Version
Deus meus, ex toto corde paenitet me omnium meorum peccatorum, eaque detestor, quia peccando, non solum poenas a Te iuste statutas promeritus sum, sed praesertim quia offendi Te, summum bonum, ac dignum qui super omnia diligaris.
Ideo firmiter propono, adiuvante gratia Tua, de cetero me non peccaturum peccandique occasiones proximas fugiturum. Amen.
About this prayer
The Act of Contrition is prayed after confessing your sins to a priest, before he gives absolution. It is not a formality tacked onto the end of Confession, it is the heart of it: a plain statement that you are sorry, and why. The traditional version above is the one most Catholics over a certain age learned by heart. The simpler version, drawn from the Rite of Penance, uses more modern language but says the same thing. The Latin version is the traditional form found in the Roman Ritual, and it is the text the English traditional version follows.
Any of these is acceptable in the confessional. Some parishes and priests have a preference; if you’re ever unsure which to use, it’s fine to ask.
When to pray it
Primarily inside the confessional, right after confessing your sins. It’s worth memorizing one version so you’re not reading it off a card in the moment, though reading it is completely fine too, no priest will think less of you for it.