Hello Vienna. Some of the envelopes that you will receive from Compassion will be prepaid, but some are not. You will want to ensure it is prepaid but checking for the words, "Postage Paid" in the upper right hand corner on the envelope. It is so wonderful that you are investing in the life of your child through correspondence! We know that children who receive letters from their sponsors actually do better overall in school and in the Compassion program. If you have any other questions on letter writing please let us know!
Note: You can also upload the letter online as a photo so that you don't have to pay postage and it arrives quicker! Compassion will print it and give it to your child and they'll still see your handwriting that way :) (Even if you send it snail mail it'll be scanned, emailed to your child's country, and then printed for your child so your child will not notice the difference... unless you added a sheet of stickers or bookmark and have to pay postage anyways)