A system and method for enabling a graphical program to receive and respond to programmatic events. The graphical program may include a graphical user interface having various user interface elements and a block diagram having a plurality of nodes indicating functionality of the graphical program. The graphical program may be configured to respond to one or more events. For each event, a portion of graphical source code may be operable to receive and respond to a respective event. The portion of graphical source code may be executable to perform a desired process or action in response to the respective event. In one embodiment, a sub-program node may be associated with each event. In another embodiment, an event structure node may be included in the block diagram, wherein the event structure node includes one or more sub-diagrams, each sub-diagram including graphical source code for responding to one or more events.