A new approach for the measurement of mechanical properties of nanoparticle aggregates is presented. Individual agglomerates are fixed onto a hard substrate and their strength is measured by nanoindentation. Images acquired using the nanoindenter itself (see figure) before and after the indentation show directly the imprints of the nanoindenter tip. It is proposed that the agglomerate strength can be correlated with the shape of the nanoindentation load-displacement curves.