Many first-generation college students -- whose parents have not obtained a four-year college degree -- experience a "cultural mismatch" due to a lack of alignment between the independent values of their university (consistent with the culture of higher education) and their own interdependent values (consistent with working-class culture). We documented this mismatch at a four-year university (n = 465), and then tested a values-affirmation intervention in a laboratory study (n = 220) that encouraged students to affirm both independent values and interdependent values. We compared this intervention, which had not previously been tested in a four-year university, to a standard values-affirmation intervention and control. This intervention increased first-generation students' perceptions of cultural match and improved achievement on a math test for all students, on average, by increasing confidence and reducing distraction on the test. Encouraging students to integrate independent and interdependent values may improve first-generation college students' experiences in higher education. [This paper was published in "Journal of Social Issues" v77 n3 p851-887 2021.]