Human beings don’t live alone. Every one of us belongs to some, typically many, social groups, organizations, and networks. These groups often provide bases for our social identities. It is also true that when we see others, we divide them into groups in order to make sense of this diverse and complex social world. Unfortunately, such divisions tend to entail the distinction between “us” and “them,” resulting in stereotypes and prejudices as well as certain types of unfair treatment of others, such as favoritism. These can be major sources of intergroup conflict. Our lab is examining cognitive and affective processes associated with various social groups based on gender, ethnicity, occupation, and some socially constructed categorizations, from a diversity of theoretical perspectives.