This chapter discusses social theories. Although personal theories known as evolutionary theories, network theories, stimulus evaluation theories, response evaluation theories, and psychological constructionist theories already accept that emotions take place in a social context, the personal mechanisms that they propose seem ultimately inadequate to account for the complexity inherent in social interactions with multiple interaction partners and across time. This has inspired the birth of social extensions of personal theories, called social theories. Social theories have added the following social mechanisms to the mechanistic toolbox: emotional contagion, social appraisal, direct relation alignment, and distributed forms of social appraisal and goal-directed processes. The chapter also presents a taxonomy of behavior in social contexts with dichotomies such as social vs. non-social, coarse vs. subtle, direct vs. indirect, communicative vs. non-communicative, intentional vs. unintentional, and stimulus-driven vs. goal-directed. The addition of social (e.g., communicative) behavior increases the power of the goal-directed theory to account for the apparent irrationality of emotions.