By Default Magento sorts the values in a drop down list alphabetically. If the values are NOT showing up in the order you want you can manually define the positions.

Magento Admin > Catalog > Attributes > Manage Attributes

Find the specific attribute. EX: Size

Click on Manage Label / Options

  • By Default all of the values will have a Position of 0
  • When a values has the same position value Magento will sort those values alphabetically

Example of sorting the Size values