Don't feel bad -- many babies get upset when it's time to get undressed. The experience of going from feeling warm and cozy to being exposed can be very uncomfortable, and he responds the only way he knows how: by wailing away. Since babies can't regulate their body temperature very well, the temperature drop of getting undressed feels dramatic, and it takes them longer to warm up once they're clothed again. Also, when you change your baby, all different parts of his body are being pushed and tugged as clothing is pulled over his head and up and down his arms and legs.
To make dressing as gentle and quick as possible, plan ahead. Have a clean diaper, baby wipes, and your child's change of clothes handy. Consider using warm diaper wipes (you can buy a wipes warmer), or moisten paper towels or a washcloth with warm water. When changing your child, drape a soft towel or blanket over his body to keep him warm. Or avoid getting him naked all at once: Unsnap the bottom part of his onesie and change his diaper while he still has the top part on. You can also try distracting him with a mobile above the changing table or by singing and talking while you undress him.
The most important thing you can do, however, is stay calm. When you get upset, your baby senses it in your face, your voice, and in the way you touch him, as you perhaps rush to get the process over with -- and that'll just get him more worked up. So take a deep breath, and remember: The crying is not about you. Reassure your baby by saying, "I understand you don't like this, sweetie. I'll just be a few more seconds. I'm putting your pajamas on now." Even though he doesn't understand your words yet, your soft, loving tone will send the right message.
Originally published in American Baby magazine, July 2004. Updated 2009.