This study treats the relationship between labor force composition and income as outlined by alternative models, competition and segregation. Analyses of 323 Israeli occupations focus on the relations between the income of European!American men and the proportions of vxmen, Arab men, and Asian!African men across the entire occupational spectrum, as well as in the core and peripheral sectors of the economy. Using two-wave regression models for 1972-1983, we find: (a) Segregation of women, Arabs, and Asian!African Jews did not significantly increase, (b) Occupations with high proportions of subordinate groups experienced a relative decline in the income of superordinates, (c) This process of competition was especially pronounced in the periphery. The results lend strong support to the competition hypothesis and only limited support to the segregation hypothesis. The findings further suggest that the structure of the economic periphery facilitates more intensive competition than in the core. Finally, we find that exclusion harms not only subordinates, but also some superordinates.