The contribution presents findings from an empirical study of 350 native and immigrant students at the point of transitions from lower into upper secondary education conducted in three secondary schools in Hamburg, Germany. Building on Boudon’s (1974) approach to explain social disparities in education, the study investigates the impact of academic majority language skills on students’ educational aspirations and expectations. Using logistic regression analysis, the question is addressed whether academic language skills can be better understood as effects of social or ethnic origin. In this context, the value of subjective data to predict the courses of action students will eventually take to translate their aspirations into attainment, and whether there are systematic differences between natives and immigrants, will be discussed. The instruments include a questionnaire, a test for cognitive abilities and a productive language test in German. The results suggest the interpretation of academic language skills as secondary effects of ethnic but not social origin. Also, the results point to strong variations in the predictive value of respondent-reported aspirations across the sample, and encourage the development of multidimensional measures of student aspirations to arrive at a better understanding of the processes that generate ethnic disparities in education.