A system and a method are disclosed for an activity manager providing a centralized component for allocating resources of a mobile computing device among various activities. An activity represents work performed using computing device resources, such as processor time, memory, storage device space or network connections. An application or system service requests generation of an activity by the activity manager, causing the activity manager to associate a priority level with the activity request and identify resources used by the activity. Based on the priority level, resources used and current resource availability of the mobile computing device, the activity manager determines when the activity is allocated mobile computing device resources. Using the priority level allows the activity manager to optimize performance of certain activities, such as activities receiving data from a user.