This is a post Loma Prieta earthquake (Oct. 1989) investigation project in learning from this damaging event. The focus of this project is to study the effects of pounding of adjacent structures against each other based on the actual damage observations. The objectives are: (1) to survey the frequency and types of pounding that occurred, (2) to evaluate analytically the effects of pounding on several buildings that had observed structural damage from pounding, (3) to investigate the adverse effects of pounding, and (4) to provide engineers with guidance to mitigate the damage from pounding. The expected research results: a summary of observed damage due to pounding, and analytical investigation to correlate with actual observed pounding damage, a proposed modeling procedure and a design method for buildings subjected to pounding, and a method of mitigating pounding damage on existing adjacent buildings. This study will lead to a better understanding of the phenomena and proper ways to mitigate the damages in connection with pounding.