Abstract: An expandable jacket that both (1) can protect a bag or knapsack worn by a user as well as the user and (2) can simulate a conventional jacket when the user is not wearing a knapsack, comprises a conventional racket and extra material affixed to the conventional jacket. Preferably, the extra material is unnecessary to the jacket's ability to be worn as a conventional jacket protecting a user from the elements, but is used to aid in allowing the expandable jacket to protect the user from the elements as well as a knapsack worn by the user. Preferably, the extra material is affixed to the rear of the jacket so that it can protect the knapsack worn by the user is worn on the user's back. When in an open mode, the extra material allows the rear of the jacket to expand to provide additional volume to the interior of the expandable jacket. When in a closed mode, the expandable jacket can be worn as a conventional jacket by the user.