Cross-cultural psychology attempts to understand the development and expression of human behavior in relation to the cultural contexts in which it occurs. It adopts the perspective of "universalism," which assumes that all human beings share basic psychological processes, but which are then shaped by cultural influences. This perspective allows for the comparison of individuals from different cultures (based on the process commonality), but also accepts behavioral variability (based on the cultural shaping). In the case of behavior that takes place during interactions between individuals coming from two (or more) cultures, the task is more complex; we now need to understand at least two sets of culture-behavior phenomena, as well as a third set--those that arise at the intersection of their relationships. In cross-cultural psychology, we have adopted concepts and methods from sociology and political science to inform work on "ethnic relations," and from cultural anthropology we have been informed in our work on the process and outcomes of "acculturation." In the former domain are phenomena such as prejudice and discrimination; in the latter are the strategies people use when in daily contact with people from other cultures (such as assimilation, integration, separation, and marginalization). These phenomena take place in cultural contexts, which need to be understood in terms of the core dimensions of cultural difference (such as diversity, equality, and conformity). During prolonged and intimate contact between persons of different cultural backgrounds, all these psychological concepts and processes, and cultural influences need to be taken into account when selecting, training, and monitoring individuals during their intercultural interactions.