Continued studies of the relative influence of parametric variables on bond strength has shown the overriding influence of surface free energy gamma sub s as compared with contact angle on prepared substrates. The effective strain value K sub o was found to be very complex. Its empirical treatment as if it consists only of uniformly distributed axial strain is a possibly useful solution which permits linking bond strength primarily to surface free energies. Also, during this third year, effort was devoted to development of nondestructive, optical, and spectrophotometric techniques for characterizing contaminants which frequently occur on substrate surfaces. Although the most sensitive techniques available were employed, they did not reveal correlations with bond strength variability observed.