Before the implications of ethnic pluralism for social behavior and attitudes can be understood, some idea of the extent of diversity among ethnic groups is necessary. This paper provides data on the ethnic groups who reside in the center of three of Connecticut's largest cities: Hartford, Bridgeport, and New Haven. The degree of similarity and dissimilarity between Connecticut's ethnic groups in social characteristics, in economic and political dimensions, and in their attitudes toward the world around them, is examined in this report. (Author/JM)