Staff members were asked to identify each youth according to his primary ethnic group, power subgroup membership, ethnic group role and status, and relations with his own and other ethnic groups. White youth were perceived as significantly less cohesive than their black or Chicano counterparts and as the group most hostile to blacks and least hostile to other groups. The major cohesion carrier among white inmates was the white power subgroup; the neo-nazi subgroup demonstrated very high cohesion and showed the most hostility toward other groups, especially blacks. Group fragmentation may have made white prisoners subject to intimidation by the increasingly powerful minority groups. Chicanos were the most cohesive group, had the smallest outgroup, and tolerated very little independence or factionalism. Blacks were nearly as cohesive as Chicanos, although blacks outnumbered Chicanos by 60 percent. Blacks were in the forefront of both racial cooperation efforts and racial conflict, and this group evidenced considerable diversity in outgroup relations. Both the black and the Chicano groups were in the process of gaining power, while the white group was in the process of losing it; each group had developed a distinctive social structure and form of adaptation to the correctional environment. Additional research is needed on prison ethnic composition, including inmate behavior patterns, differences in inmate behavior in prisons dominated by different groups, and the nature of alliances in correctional institutions. Three references are included.