When two or more ethnic or racial groups come together, their interactions typically range along a continuum from total tolerance to total intolerance. These interactions occur whether the groups are from within the same society or completely foreign societies and may lead to a variety of outcomes based on each group's level of tolerance of the "other."


Assimilation represents the extreme of complete tolerance. Through the process of assimilation, two or more formerly separate cultures are blended together to create a common culture. Assimilation may involve the construction of a wholly new culture, with all the contributing cultures disappearing. However, normally, assimilation involves the minority subsuming its culture and accepting the culture of the majority race or ethnic group.


Segregation involves the separation of two ethnic or racial groups within a society. The separation includes workplaces, residences and social institutions. Segregation may be either voluntary or involuntary. Voluntary segregation may be a result of a particular ethnic group preferring to live and work closely together. Involuntary segregation may be “de jure” or “de facto.” “De jure” segregation is separation of groups by legal means. Apartheid in South Africa was a legal system of segregation. “De facto” segregation is segregation in fact or through unwritten customs.


Slavery is the legal ownership of one group by the other. The group with ownership controls every aspect of the enslaved individuals' lives such as reproduction, type of employment and religion. Slavery is typically applied to a minority group for financial gain of the majority.


Expulsion, also known as population transfer, is the forced removal of the population that occupies a territory by another group that lays claim to that territory. The removal may be to a segregated portion of the state or completely outside the state. During World War II, Franklin Roosevelt ordered the removal of Japanese citizens to internment camps due to the possibility of their constituting a threat to national security. This was an example of population transfer. In many disputed territories throughout the world, expulsion occurs on a regular basis as one group or the other gains control and removes members of the opposing culture.


The extreme manifestation of intolerance is genocide. Genocide involves the systematic killing of a minority population by the leadership of the majority population. Genocide is typically state-sponsored, with the majority calling for the destruction of the minority due to their perception of the majority culture as inferior or dangerous in some way.