In this study I examine the academic self-concept (ASC) of students who changed from vocational to academic tracking at the transition to upper secondary education in Germany. I ask (1) how their ASC differs to the ASC of their established peers in academic tracking, and (2) how their ASC is affected by the change in the learning environment. Using a subsample of the German National Educational Panel Study (NEPS; N = 4109), findings show that newcomers to academic tracking have a stronger ASC than their peers. However, social differences between the social milieu of origin and the one prevailing at school significantly reduce the ASC. These differences are interpreted as being social-habitual and tested via socioeconomic status, cultural capital, and parental solidarity expectations at the school level. Results differ according to immigrant origin; immigrant newcomers to academic tracking have higher ASC than their established peers, and context effects are more influential. I complement previous research by using a quantitative approach to test the theoretical mechanisms of a qualitative research perspective on upward mobility.