Students preparing a vocational diploma at what is called “level 5” (CAP or BEP) have a choice between a vocational high school and apprenticeship under a program that alternates between classroom instruction and work experience (formation professionnelle alternée). Drawing on data from a panel of secondary-school pupils, this article looks at the determinants of the choice between the two paths and seeks to measure the effect of an apprenticeship spell on scholastic achievement. As regards the choice of apprenticeship over vocational high school, the past educational path remains decisive, particularly a low educational attainment at the end of the third year of secondary school, early streaming in the second or third year of secondary school towards classes with a pre-vocational curriculum, and enrolment in a school located in a “priority education zone” (ZEP). However, the strongest factor is the local context. The reason is that the share of apprenticeship in the regional system of “level 5” training programs is a powerful factor in determining such a choice, especially for the weakest pupils. As regards the impact on scholastic achievement, if we take into account the endogeneity of apprenticeship, we can identify a negative but non-significant effect of this type of training on the probability of dropping out of school, and a significant positive effect on the probability of obtaining the diploma. In sum, for pupils who have been advised to enter a BEP or CAP programme, an apprenticeship spell gives them a better chance of obtaining the diploma than enrolment in a vocational high school.