Segregation patterns of several pod shapes of Phaseolus vulgaris L. cv Tendercrop, were studied. The causes of build-up of off-type pods in a seed stock were examined as were possible means of reversing the buildup. Natural selection factors such as germination, vigor, earliness , and ease of threshing, favored the off-types. Careful, selective milling was found to be an aid to roguing in keeping stock seed as free as possible of the off-type pods.