IN THIS CHAPTER, WE EXAMINE the social groups that often exist in human societies: kin-based groups, economic groups, status groups, and political groups. These groups are based on different individual interests—genetic interests (kin groups), economic interests (classes and companies), status interests (status groups), and political interests (political groups). People in all societies form groups with kin. In larger and more populous societies, people who have similar economic interests, people who share a common lifestyle, or people who have similar political interests often group together and can be linked by social networks. Whether and how individuals with similar interests coalesce into groups in which the members are linked by social networks differs from society to society.