This paper reviews the concepts of acculturation and adaptation to provide a framework for understanding the highly variable relationship between acculturation and mental health in refugee populations. It begins with an extended definition and discussion of the concepts of acculturation and adaptation. The characteristics of acculturating groups and dominant groups are briefly described, and a schema is developed to illustrate the concept of acculturative stress. Experiences related to psychological acculturation and adaptation are classified and described according to the phase of the acculturation process: pre-departure, flight, first asylum, claimant status, settlement, and adaptation. The paper concludes with five general observations on acculturation stress with regard to refugees: (1) they are powerless with respect to dominant groups both before and after departure; (2) countries of first asylum are often least able to assimilate new arrivals; (3) lack of voluntariness or mobility creates stress; (4) the probable sequence of acculturation for refugees is highly likely to lead to psychological and social problems; and (5) the major stressors are in the early phases of the refugee experience. References are included. (TE)