Environment sensitive crack growth by dissolution related mechanisms is capable of prediction on the basis of appropriate electrochemical measurements that define the potential ranges for cracking and the upper bound crack velocities for potent environments. Where the cracking environment is locally generated from an innocuous bulk environment predictability is more difficult, but there are the beginnings of indications of correlations between pitting propensity and the incidence of cracking in such circumstances. There is now sufficient data for a variety of systems to show that the relative time dependencies of film growth and plastic straining of the underlying metal determine whether or not cracking will occur, but the quantification of such a model has not yet resulted in accurate prediction of the limiting plastic strain rate. This is probably because little is yet known about the details of the conditions at crack tips. For intergranular cracking it is likely that chemical heterogeneity at the grain boundaries will play a critical role, but little is known about why segregating species facilitate cracking in such regions. Similarly, in relation to transgranular cracking, the initiation of the latter at emergent slip steps suggests a critical role for plastic strain, but the reasons for the localized embrittlement of the metal in the crack tip region remain to be elucidated.