Two competing views of determinants of immigrants' perceptions of U.S. society and perceptions of discrimination against their own group are examined. Assimilation theory suggests a process leading to lesser discrimination and a more favorable evaluation of the host society as immigrants' economic position, and their knowledge of the culture and language improve. More recent conflict theories indicate a possible reversal in this causal sequence: greater familiarity with the culture and language and some economic advancement can lead to greater consciousness of the reality of discrimination and a more critical appraisal of the host society. These competing perspectives are examined on samples of Cuban and Mexican immigrants interviewed at the moment of arrival in the U.S. and reinterviewed three years after. Bivariate and multivariate regression results are mixed, but lean definitely in the direction of the conflictlconsciousness hypothesis. A LISREL model of immigrants' perceptions of society and discrimination confirms the basic similarity of causal effects across the two immigrant groups and the general agreement of those effects with conflict theory predictions. Implications of these findings are discussed.