These symposium proceedings address exciting aspects of the interaction of very high intensity laser pulses with plasmas in a special strong field regime where electron motion is highly relativistic. The interdisciplinary subject matter includes the basic physics of notable laser-driven conversion processes and some important applications of these processes. Important conversion processes dealt with here that are associated with these laser-plasma interactions are the acceleration of ions and electrons by laser pulses and the laser generation of intense harmonic radiation, as well as other intense xuv and x-ray radiation. Noteworthy medical applications include the potential use of laser-driven ion beams for ion therapy for cancer and the development of x-ray phase contrast imaging. The diagnostic use of proton beams in experiments and of ions for ion imaging represent interesting nonmedical applications that are described.