Choosing a godmother for your baby isn't a decision to take lightly. In some cases, this person will be responsible for raising your child if something happens to you and your spouse. At the same time, a godmother is someone you want your child to grow up having a close relationship with. It pays to weigh the decision carefully before asking a friend because that person may not always be in your life. Once you've made the choice, asking her to take on the role takes a bit of tact and planning so you're both on the same page.
Define the role of godmother. A godmother might be someone who shops with your child as she gets older, shows up to support her at school plays or graduations, or is available for advice when she doesn't feel comfortable talking to you. It also might be a person who would assume guardianship of your baby if you and your spouse died. Sometimes a godmother is appointed to help steer a child on her spiritual path. Defining what you expect from your friend allows her to make the decision to accept or decline based on whether she's comfortable with the duties.
Formally ask your friend to be godmother. Set aside a time when you can discuss the role with your friend. You might do this at your favorite coffee shop or on the swing in your backyard.
Allow your friend to think through the decision. This isn't a role that should be taken lightly, so give your friend a couple of hours or a few days to think about what you're asking of her. This waiting period is beneficial for you, even if waiting for an answer is hard, because you want a godmother who takes her duties seriously, not one who accepts on the spot without weighing the gravity of the role.
Talk to your clergy person. In some religions, including Catholicism, a priest or pastor must approve a parent's decision regarding a godmother. In some cases, godmothers are asked to take classes or undergo certain ceremonies to ensure they are prepared to take on the role. In many instances, a godmother is asked to be present at the baptism of the baby.