In this paper we discuss how interactive ceilings may improve productivity and collaboration in office environments. The ceiling of an office offers an unobtrusive, unobstructed display and input area which is accessible to all persons in the room. Therefore, enhancing ceilings with input and display capabilities allows for a range of new single-user and multi-user applications such as status indicators, unobtrusive notifications, in-house navigation and collaborative work areas. However, ergonomic constraints limit the application space. To investigate such constraints we built a working prototype of an interactive ceiling. Currently, we are conducting a study investigating which areas on the ceiling may be used for displaying notifications and content.