We discuss the possibility of establishing a set of observational parameters for radio galaxies which could be used to study radio source evolution in the same way that the Hertzsprung-Russell diagram is used to understand stellar evolution. As a first step towards a radio H-R diagram, we show that the FRI/II break is a function of both radio and optical luminosity. This result combined with the radio linear size/luminosity diagram suggests that the FR III break is very sharp and the two morphological classes probably have an evolutionary connection.