Heat oven to 400°F. In large bowl, stir sugar, butter, shortening and eggs with spoon until mixed. Stir in flour, cream of tartar, baking soda and salt.
Shape dough by rounded teaspoonfuls into balls. Roll balls in colored sugar until coated. On ungreased cookie sheet, place balls about 2 inches apart.
Bake 8 to 10 minutes or until centers are almost set. Cool 1 minute; remove from cookie sheet to wire rack.