AbstractOf nine glassy polymers so far investigated, eight yield evidence that fracture propagation involves the formation and breaking of craze material. All eight produce fracture surfaces exhibiting interference colors to one extent or another and even the colorless areas cause low angle x‐ray scattering. Ranked in terms of decreasing ease of colored surface formation, these polymers are poly(methyl methacrylate), poly(ethyl methacrylate), polystyrene, acrylonitrile—styrene copolymer, poly‐α‐methylstyrene, poly(vinyl acetate), a polyhydroxy ether, and polycarbonate. Only rigid poly(vinyl chloride) has failed to show evidence of precrack craze f