Line 24 muffin tins with paper muffin liners. (if you want fuller size muffins, then only do 20 muffins) You can also skip the paper liners and use a silicone muffin pan. I use mine all the time and love it.
In a large bowl mix pumpkin and the box of cake mix. Mix well with an electric mixer.
Spoon into your cupcake pan using a large ice cream scoop. I personally have this 3 pack of cookie scoops and they are on sale right now. If you do not have a scoop you can also use a 1/4 cup measuring cup to scoop the batter.
Bake for 18-20 minutes. Test for doneness with a toothpick.