We have undertaken a series of studies to better understand the response of ultrasound contrast microbubbles to pulsed ultrasound. Toward this end we have used acoustical and optical scattering techniques. The acoustic interrogation of shell-disrupted microbubbles immediately following HIFU was used to monitor microbubble (or fragmented daughter) dissolution. Results were compared to calculations, assuming a simple Gaussian distribution of fragmented microbubbles and the dissolution characteristics of a mixed-gas system (such as a perfluorocarbon gas bubble in air-saturated water). Good results were obtained by considering a multi-modal bubble size distribution. That is, the HIFU pulse created a distribution of smaller bubbles. In order to follow the instantaneous motion of a single microbubble during pulsed ultrasound, light scattering was employed. For this experiment, a diagnostic ultrasound system was used to force the microbubble into oscillation. Light scattered off the microbubble was collected by a photodetector. A simple bubble dynamics model was used to fit the data. At low pressures, consecutive data segments were averaged to increase the signal/noise. At higher pressures, the bubble (size or shell) properties required systematic adjustment in order to obtain a good fit, suggesting that the bubble evolved with each pulse.