This article is a review of the techniques for characterizing ultrasound surgical devices, as a guide to those undertaking a program of measurement, and as a basis for further standardization of those methods. The review covers both acoustic and nonacoustic measurements, with an emphasis on proper techniques, devices, and analyses according to the IEC Standard 61847. Low-frequency hydrophone measurements are presented, which are centered on simple acoustic theory. Inertial cavitation measurements are described based on detailed analyses of shock wave propagation. Cutting force tests are also presented as a basis for determining relative performance characteristics and determining mechanisms of action. Example data from each type of test are given. Comparison between acoustic output measurements, in vitro data, and clinical outcomes help establish that inertial cavitation is the predominant mechanism of soft tissue erosion and emulsification. The test results also demonstrate approaches to improving efficiency while minimizing undesired effects. Finally, recommendations are made for updates to the 61847 Standard and for other device labeling that would improve patient safety.