In an effort to promote an evolutionary view of culture, the Tucson Papago society was examined in terms of Fredrick Barth's theory that: (1) an ethnic group may be involved in complex institutional sharing and still maintain its identity; (2) there is a structuring of interaction in institutional sharing such that each group is defined by the sharing; and (3) a common culture is a result of structured institutional sharing. Papago patterns of institutional sharing with the dominant society were traced from 1687 to the present, and current examples of "adaptations" of institutional sharing were identified. Specific areas examined were: (1) the Community Economic Opportunity and the Tucson Indian Center (examples of reinforced social hierarchy); (2) the employment hierarchy (institutionalized poverty); (3) housing (systematic constraints acting to keep the Papago in the low rent area of South Tucson); (4) the Public Health Service (a facility serving the Papago precisely because they are Papago and, therefore, eligible); (5) entertainment (in the form of drinking in bars owned by Anglos). Evidence indicated that an ethnic group may be involved in complex institutional sharing with a dominant group and still maintain its identity and that this socio-cultural group can be defined to a large extent by its participation in mainstream institutions. (JC)