Although ethnicity has generally been relegated to secondary status as an explanatory factor in urban political participation studies, this research hypothesizes that ethnicity plays a major role in determining communal political participation. Communal participation is defined as participation in which the individual acts in concert with or on behalf of members of the wider community. The study was based on a 1973 survey of Jews, Irish, Blacks, Cubans, Dominicans, and Puerto Ricans in an urban Manhattan neighborhood. Regression analyses were performed relating the ethnic identities of these six groups to their political attitudes (awareness, involvement, knowledge, cynicism, and efficacy), and political participation (contacting officials, joining organizations, signing petitions, and attending protests). Findings indicated that one's ethnic identity affected political participation in three ways. Ethnic groups were predisposed to (1) participate or not participate in political culture according to group value orientations; (2) exhibit interest or lack of interest in political affairs according to the political consciousness and activity of one's ethnic group; and (3) act either frequently or infrequently in a cooperative manner with people who are outside of one's primary social network in accordance with group interaction norms. The conclusion is that ethnicity has a major effect on the level of participant political culture and is largely independent of social class. Tables and diagrams are included. (Author/DB)