Research on the effect of education on political orientations has typically focused on the degree obtained rather than the specific exposure to different fields of study. Studies investigating political orientations in higher education typically struggle with identifying causal effects due to their unit of measure, the degree obtained. Yet the differences in political orientations between fields of study among the college-educated are apparent. In this study, we use micro-data as a more granular measure of exposure to education, specifically measuring the social science and humanities course credits of undergraduate students at a large public university in California. By measuring exposure using courses within these departments, we can disentangle the selection effects from the causal impact of students’ exposure to social sciences or humanities. Since the treatment effect of exposure doesn’t depend on the student’s chosen degree, in contrast to previous research. Employing recent methodological advances in Difference-in-Differences estimators, we test the causal impact of exposure to social science and humanities courses on political orientation using inverse probability weighting. Combining the UCI MUST survey data with course data, we find that exposure to social science and humanities courses causally predicts a leftward shift in political orientations. Our analysis reveals that the effect of exposure is both significant and robust, accounting for self-selection biases and peer influences. The young and highly educated are socialized by exposure to these courses to become more left-leaning than their peers. Our findings highlight the consequences of overlooking exposure when identifying socialization effects among the highly educated.