Local damage processes that have been reported for ductile and brittle macroscopic behaviors are shown here to provide a possible link between these two contrasting behaviors. Using a local progressive damage law within a linear tensorial elastic interaction model, we reproduce experimentally observed macroscopic non-linear behaviors that continuously range from ductility with diffuse damage to brittleness with localized damage. The model exhibits power law distributions of damage events in space and size domains. The diffuse-localized and induced ductile-brittle transition appear to be controlled by the internal friction angle which influences the local interaction geometry. ¿ 1999 American Geophysical Union