Examples are disclosed that relate to a mobile device configured to change a feature set in response to detecting that a case is attached to the mobile device. One example provides a method enacted on a mobile device. The method comprises operating the mobile device with a first feature set. The first feature set comprises one or more features enabled when a case is not attached to the mobile device. The method further comprises detecting that the case is attached to the mobile device and an identity of the case by using a magnetic sensor. The method further comprises operating the mobile device with a second feature set that is different from the first feature set in response to detecting that the case is attached to the mobile device. The second feature set is selected based upon the identity of the case.