Grain boundary ledges and/or dislocations have been observed in a wide variety of materials by a number of investigators using transmission electron microscopy (TEM) techniques. These defects can be expected to have interesting implications in terms of grain boundary precipitation reactions and creep behavior. In this paper we describe some of our TEM observations of grain boundary ledges in a specimen of type 304 stainless steel which was solution treated at 1040°C, quenched, cold worked 2%, and aged for 15 minutes at 850°C.The configuration of the ledges can be observed in Fig. 1. For the diffracting conditions in Fig. 1 both bright and dark contrast effects are associated with many of the ledges. Strong contrast of this sort has been observed by other investigators. This strong contrast is not typical, however, as can be seen on comparison with Figs. 2 and 3, which show the same grain boundary under different diffracting conditions.