A christening card can be written either to the baby, the parents, or both. It is often a great idea to address the card to the baby, especially if you are the godparent, because the card is likely kept for the child to read when they are older. Writing directly to the baby makes the message personal and memorable. However, for grandparents, family friends, or if you feel uncomfortable writing to a baby who cannot read yet, addressing the card to the parents is also perfectly acceptable. Many people also choose to write the card to both the parents and the baby together, which is a good middle ground. The choice can also depend on the wording on the front of the card. For example, if the card says "On Your Christening Day," it often lends itself to being addressed to the baby. If it references the parents or the family, then writing to the parents makes sense. In conclusion, there is no strict rule; it depends on your relationship with the family and personal comfort. Writing to the baby, to the parents, or to both are all considered appropriate for a christening card.