This article focuses on which aspects of the learning environment, aimed at fostering career learning, correspond with the development of career competencies among students (aged 12-19 years) enrolled in prevocational and secondary vocational education in The Netherlands. Aspects of the learning environment that are taken into account here are the following: career orientation and guidance methods used, instruments implemented, and the degree to which the curriculum is practice-based and dialogical. In the study, three career competencies are identified: career reflection (reflective behaviour), career forming (proactive behaviour), and networking (interactive behaviour). To research the relationship between the learning environment and the presence of career competencies, a study was done among 3499 students and 166 teachers in 226 classes in 34 schools. The results show that career guidance in school, in which a dialogue takes place with the student about concrete experiences and which is focused on the future, contributes most to the presence of career competencies among students. Without this dialogue, career guidance methods and instruments barely contribute to the acquisition of career competencies. (Contains 1 figure and 2 tables.)