A classification system that has been developed for the characterization of the excavatability of soils and rocks is reviewed briefly. The system comprises an adaption of the Norwegian Q classification developed for the characterization of tunnel support. It enables a through-going classification of geotechnical materials from soft soils to hard rocks to be made. Characterization with regard to single tine ripping and bucket hoeing is also provided. The system has been applied for a number of years to a variety of problems and has generally enabled reasonably accurate predictions to be made of mechanical excavatability. Several case histories are described in the paper. These include the diggability of a 30 km long trench for a 2.3 m diameter pipeline, the rippability and dozability of construction materials from shallow borrow pits in geological deposits of limited depth, the excavatability of the terraces for two 50 ML bulk water storage reservoirs, and the excavatability by ripping and blasting of a railway cutting of some 850 000 m3 in volume. It is demonstrated that the variable conditions in each of the examples could be reasonably accurately characterized for excavatability by means of the classification system; the latter is based on the rockmass parameters which affect ploughsharing or equivalent comminution processes.