In the U.S. context, Ogbu concluded that among U.S. Americans there are "voluntary minorities" (groups of immigrants who chose to come to the United States, and their descendants) versus "involuntary" or "caste-like" minorities (descendants of groups of persons who found themselves in the United States, or under United States jurisdiction, against their will). Voluntary minorities (e.g. Korean-Americans) tend to manifest non-oppositional secondary differences with the dominant culture. On the other hand, involuntary minorities (e.g. Native Americans) tend to manifest oppositional secondary differences with the dominant culture. However, both voluntary non-oppositional cultural subjects and involuntary oppositional cultural subjects are required to adhere to dominant (white) American cultural frames of reference if they want to acquire upward social mobility.