Your Method

• Cake mixes have been designed to be forgiving, but if you stray too far from the directions, you may end up with a flat cake. A cake that's too runny may not rise properly, so be sure to use the amount of oil and water recommended on the package. If you enhance the mix with additional ingredients, such as melted butter or sour cream, use only a few tablespoons and reduce the oil a bit to compensate. Use the right size cake pan, as well. If you use a very large pan, the cake will remain relatively flat. Although it still rises, it won't appear to rise as much because of the size of the pan.

Old Cake Mix

• Sometimes a cake mix doesn't rise in the oven is because the cake mix is old, which means the baking powder in the cake mix is old, as well. Baking powder, a combination of baking soda, cornstarch and cream of tartar, has a shelf-life of about six months to 1 year. After that, the baking powder begins to lose its effectiveness and may not cause the cake to rise as much as it should.

Into the Oven

• Baking powder, the most common leavener in cake mixes, is double-acting. This means it begins to form bubbles when combined with moisture and gets a second boost of bubbles when introduced to the heat of the oven. Theoretically, you can wait a while before baking a cake mix batter because the second round of bubbles that form in the oven cause it to rise, even if the first bubbles have already dissipated. However, baking powder isn't indestructible, and if you wait too long, you may get a dense, flat cake. Get a cake into the oven within 15 to 20 minutes of mixing it. Don't refrigerate raw batter overnight or freeze it.

Oven Temperature

• The best temperature for baking cakes is somewhere between 325 and 375 degrees Fahrenheit. The heat at this temperature causes the cake batter to form lots of bubbles quickly so the cake rises. The temperature isn't so high, though, that it burns or dries out the cake. If the oven temperature is too low, the cake might not rise properly.