Crenulation cleavages are zones of mineral differentiation coincident with the limbs of microfolds in crenulated rock fabrics. They are subplanar domains of highly oriented micaceous material which constitute preferred sites of parting in the rocks. Their microfabrics group into two classes-either thin sharply defined cleavages or wide diffuse cleavage zones with indistinct boundaries. Existing classifications and terminology for classifying and describing these morphological types of crenulation cleavage are unsuitable because they do not adequately describe the cleavages, have genetic connotations, and have limitations in their application. A morphologic classification based on distinctive features of the cleavage is therefore proposed. This classification, incorporating new terminology (the prefix terms discrete and zonal), essentially sharpens the distinction between the existing classes of crenulation cleavage with the aim of providing a more objective basis for describing their microfabrics.