Breakage and selection functions for wet-phase grinding of carbon in a stirred bead mill have been determined by a method based on Kapur's first-order approximate solution. This allows calculation of curves of B-ij = F (x(i)/x(j)) which are used to characterise the fragmentation mechanisms in terms of either abrasion or fragmentation. Comparison of the mechanisms identified in this way, with observation of the fragments produced under different grinding conditions by means of a scanning electron microscope coupled with image analysis confirms the validity of these conclusions.