This chapter introduces the principles of homogeneity, including the basic meaning, simple measures, pros and cons, and its significance, in order to understand the node properties of social networks. This chapter then discusses the impact of homogeneity on social networks, introduces affiliation networks, expands on the triadic closures-focal closures and membership closures mentioned in the previous chapters. It also describes the representation, measurement, analysis, and description of two-mode networks, and finally analyzes the segregation model.