Criteria for the classification of Red Earth soils into groups reflecting differences in their productive potenrial were investigated on three sites near Cobar, New South Wales. Five features were shown to be useful by cluster and discriminate analysis of an extensive data set. A field-based classification using six very similar criteria was also tested and shown to agree with the cluster method. Laboratory tests for stability and fertility of the surface soil layer from each class indicated a significant difference between classes, and a narrow range of values for an individual class. Herbage production on quadrats over the range of soil surface condition also consistently reflected the classification. When the method was tested with three personnel previously unfamiliar with the criteria, good agreement with the original experimental set was obtained.