The papers in this issue are from a conference held in May 2002 at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. This conference brought together researchers from all current western gorilla sites for the first time with the aim of synthesizing the most current information available on western gorilla behavioral ecology. Our goal was to assess the degree of behavioral diversity in gorillas in light of our current understanding of social evolution. The articles include 1) synopses of the current information on western gorilla foraging strategy, social behavior, life history, and genetic variation; 2) more-detailed descriptions of home-range use and intergroup encounters across sites; and 3) the first description of the social behavior of western gorilla females.