A multitasking system and method are provided. The system and method allows a mobile device with a limited amount of resources to execute applications in full and mini modes, thereby using a relatively small amount of resources and efficiently using the execution screens. The method includes detecting a first event for executing a first application, identifying the type of first execution event, executing the first application in at least one of a full mode and a mini mode according to the type of first execution event, and displaying an execution screen of the first application executed in the at least one mode.