The children of immigrants usually make more ambitious enrolment choices than native students with comparable socioeconomic status and academic achievement. Less is known about how ethnic choice effects vary by socioeconomic status and previous achievement simultaneously, and whether they only hold true for some immigrant–native comparisons. Moreover, few studies investigate outcomes after the educational transition, so the consequences of ambitious choices remain unclear. I investigate immigrant–native gaps in the decision to enroll in academic upper secondary education and in outcomes after the transition for two cohorts of French students. I find that ethnic choice effects are positive only for students with an intermediate or working class background, and are largest for those with lower to middle achievement from the working class. Migrant disadvantages in outcomes after the transition were reduced between cohorts. In the latest cohort, immigrant-origin and native students enrolled in academic upper secondary were equally likely to complete the track and enroll in tertiary education. However, immigrant-origin students were still disadvantaged in terms of graduation track, grades, and timing. Using counterfactual reweighting strategies, I show that similar and substantial portions of these disadvantages were explained by the ambitious academic choices and lower prior performance of immigrant-origin students. However, while their ambitious choices also increase enrolment rates and hence overall attainment for immigrant-origin students, their lower prior performance reduces both. I suggest that policies should reduce immigrant disadvantages in early achievement to allow high-aspiring, yet often disadvantaged, immigrant-origin students to succeed in ambitious educational paths.