The Twenty Sixth Jerusalem Symposium reflected the high standards of these distinguished scientific meetings, which convene once a year at the Israel Academy of Sciences and Humanities in Jerusalem to discuss a specific topic in the broad area of quantum chemistry and biochemistry. The topic at this year's Jerusalem Symposium was reaction dynamics in clusters and condensed phases, which constitutes a truly interdisciplinary subject of central interest in the areas of chemical dynamics, kinetics, phohemistry and condensed matter chemical physics. The main theme of the Symposium was built around the exploration of the interrelationship between the dynamics in large finite clusters and in infinite bulk systems. The main issues addressed microscopic and macroscopic sol vation phenomena, cluster and bulk spectroscopy, photodissociation and vibrational predissociation, cage effects, interphase dynamics, reaction dynamics and energy transfer in clusters, dense fluids, liquids, solids and biophysical systems. The interdisciplinary nature of this research area was deliberated by intensive and extensive interactions between modern theory and advanced experimental methods. This volume provides a record of the invited lectures at the Symposium.