This paper describes a new test machine that has been designed to measure the strength of single particles in the size range of 10(2)-10(3) mum. The device is a vibrating box that subjects each particle in the sample to a large number of impacts of known but variable strength. By tracking the size and shape of the particles as a function of the number of impacts, their strength characteristics against the mechanisms of fracture, fatigue and attrition can be differentiated. The number of particles tested in one sample is restricted in order to make any particle-particle interaction negligible but is sufficiently large that the distribution of these characteristics can be determined. The instrument has wide application to particle systems where breakage occurs, whether desired or not. It was particularly developed to test granules of different and complex structure. Some experimental results are presented in this paper to illustrate the test's effectiveness in this regard.