Techniques have been developed for measuring the fractional area of an adhesive joint that has failed adhesively (near or at the substrate/adhesive interface) and cohesively (in adhesive). These techniques involve microscopy, beta ray backscattering and light reflection from an array of positions on the fracture surfaces of the failed joint. The beta ray count rate depends upon the elemental composition and is, therefore, different for the substrate and adhesive. The count rate correlates with the fractional area that failed adhesively and cohesively, for the localized spot that is monitored. A map of the count rate values correlates with microscopic photographs which also reveal adhesive vs. cohesive failure. The beta ray and reflection techniques are conducive to automatic computerized mapping and averaging, whereas the photographic techniques are not. -- AATA