Abstract: A method and apparatus for sensing state of a waste toner box of a system during an electrophotographic developing process. The apparatus and method sense whether or not a waste toner receptacle has been installed prior to initiation of the development process and whether the receptacle is full of waste toner. The receptacle has a semi-transparent body for storing a waste toner removed from a cleaning blade, a photosensor for generating a signal representing whether the waste toner stored in the waste toner receptacle has substantial filled the receptacle as well as whether the waste toner receptacle has been installed.