Maneuvering the complexities of social relations has required that brains of social mammals develop specialized circuitry to detect, process, and manage this information. This chapter discusses the field of social neuroscience, an interdisciplinary field focused on the behaviors and circuits underlying social life. Integrative multilevel analysis that draws from the variety of disciplines involved in the study of social neuroscience is essential for the development of comprehensive models of social behavior that take into account interactions between environmental and genetic factors in determining this behavior. This chapter provides a brief overview of the hierarchical and heterarchical organization of neural structures and how these structures influence and shape social perception and behavior. In particular, different levels of the neural hierarchy—the neuraxis—vary in the complexity, integration, and automaticity of their neural organization and information processing capacities. These structural and functional differences impact underlying approach and withdrawal tendencies, which influence interactions with the environment, perception and evaluation of social information, and subsequent behavior. A multilevel analysis in social neuroscience can uncover the complex interplay between the social environment and the biological structures—as well as their physical underpinnings—that make up and explain social life.