PREHEAT oven to 350° F. Paper-line or grease 24 muffin cups.
BLEND cake mix, pumpkin, eggs, oil and water in large mixer bowl until moistened. Beat on medium speed for 2 minutes. Pour batter into prepared muffin cups, filling 3/4 full.
BAKE for 18 to 23 minutes or until wooden pick inserted in center comes out clean. Cool in pans on wire racks for 10 minutes; remove to wire racks to cool completely. Spread cupcakes with frosting. Decorate with assorted sprinkles, if desired.