It is well known that the atomic structure of an interface has some influence on its properties and thus on the properties of a poly crystalline ensemble as a whole. However, with the enormously large number of interface structures possible and no cohesive framework within which to understand them, it seems a hopeless task to search for structure-property relationships for all interfaces. Rather, we have adopted the viewpoint that interfaces may be grossly categorized into low-misorientation angle/special boundaries and random boundaries with a subsequent two-state division in their properties. We will discuss a simple methodology for examining stress-voiding and electromigration failures in thin metallic interconnects that takes the differing abilities of the interface classes to contribute to failure into account. We thus provide one of the first attempts to account consistently for the atomic structure of an interface and the macroscopic behavior observed in a poly crystalline system.