Acoustic emission (AE) makes use of the ultrasonic signals which result from the release of energy within a sample or structure as it is subjected to stress. The physical source of these signals and their amplitudes is determined by the condition of the material and structure and the manner of stress application. AE is routinely used as an inspection technique to detect crack growth in metal structures subjected to pressurization or mechanical forces. It is also routinely used to detect fiber breakage in composite structures such as filament wound pressure vessels and utility bucket trucks [1,2,3]. A technique to quantify prior impact damage using the AE generated by low level heating in polymer-based composites previously damaged by mechanical deformation has been investigated by the NSWC team [4] and by others [5,6]. The studies presented here address the use of AE to characterize the condition of the bondlines between materials.