<p>Social interaction is a process in which two or more conspecific individual information and engage with one another, mutually influencing each other’s behavior. Within this framework, social cognition and social memory constitute fundamental components that enable adaptive social behaviors. Deficits in social cognition and memory have been implicated in various psychiatric disorders since social memory itself represents a core expression of episodic memory. In this review, we summarize the theoretical evolution of understanding the social cognitive memory from the grandmother cell hypothesis to the concept cells and engram assemblies, and highlight key neural mechanistic advances derived from studies in mice. We particularly focus on the social engram assemblies and their functions in the medial prefrontal cortex (mPFC) and further discuss the potential role of neural manifold analysis and neural attractor networks.</p>