The volume includes an introduction and an overview of the field and makes the case that employee affinity groups are a burgeoning phenomenon with great philanthropic potential. Since 2000 the number of affinity groups has grown sharply and now includes Asian American, Latino, LGBT, and Native American groups. They are seen as having the potential to simultaneously meet corporate and employee objectives. In the sample under examination the total aggregated number of employees engaged in affinity groups may exceed 16,000. These employee networks point to a potential sizable, pooled and emergent source of philanthropic capital.