In a graphics processing system, a driver for the graphics processing pipeline can include conditional graphics processing tasks in the graphics processing tasks that are to be executed by the graphics processing pipeline to generate a render output required by an application. Each such conditional task has associated with it a condition to be used by the graphics processing pipeline to determine whether to execute processing for the task or not and a region of the render output over which the processing for the task will be executed when the condition for the task is met. The graphics processing pipeline determines whether the condition associated with the task has been met, and only executes the processing for the task if the condition associated with the task has been met.