Using data collected among Mexican-American adolescents, this paper tests a model positing an effect of ethnic consciousness on system blame, and an effect of system blame on political leftism. For the sample as a whole, results support the model, although the effect of system blame on leftism is weak. Further analysis reveals an interactive relationship such that system blame has a significant effect on leftism among respondents whose father's occupation is not low (nonmarginals), but no effect among respondents whose father's occupation is low (marginals). The interaction is apparently due to a greater relevance of system blame items to nonmarginal respondents. Students of lower-class politics have devoted much attention to the hypothesis asserting an association between class consciousness and political leftism. But such inquiries have been restricted to adult proletarians, to the exclusion of their younger counterparts. Yet, the class consciousness-leftism hypothesis clamors for investigation among pre-adults. Pre-adults know about class differences (Simmons and Rosenberg; Straddling and Zureik; Tudor) and they share their family's lot in life. Moreover, it is plausible to assume that those in the anteroom of adulthood might organize their political perspectives much as, according to theory, adults are likely to organize theirs. The purpose of this paper is to explore the association between class consciousness and leftism in a Mexican-American adolescent sample. Since the subjects are members of a distinct ethnic group, it further attempts to assess the relationship between ethnic consciousness and class consciousness. A major difficulty in pursuing these research interests is the relative scarcity of appropriate settings. With the recent recurrence of Mexican-American militancy, manifested in such developments as the growth of student activism and the United Farm Workers movement, it would seem that suitable settings would abound. But this is not the case for two reasons. First, in many places respondents might be reluctant to express openly their political views for fear of reprisal from the dominant elements in the community. Second, the usual case is that leftist or quasileftist views survive only within a small segment of the target population. In such circumstances, the study of leftism within the broader community would be little more than an idle exercise. Because its political situation did not seem to present these problems, Crystal City, Texas, offered an ideal research site. Crystal City is a small South Texas community with a population of about