The provision of workplace-based experiences (internship/placement) is an important component of the training program of students attending vocational education courses. Regarding the impact of such experiences on vocational development, research results are not conclusive enough, mainly, if we consider the theoretical expectation that work experiences clearly affect the vocational development of adolescents. The main purpose of this study is to clarify the relationship between work experience quality and students' vocational development. Using a longitudinal design (pre- and post internship), we conducted a study that explores the relationship between perceived qualities of the training experience (autonomy, colleagues feedback, social support, learning opportunities, supervisor training, supervisor support) and the different dimensions of career exploration (beliefs, behaviors, and reactions), in a sample of Portuguese high school students (N = 346, twelfth grade). Overall, results suggest that the quality of work experience is relevant for the vocational development of students. With the exception of supervisor training, all other internship qualities were single significant predictors of career exploration over the internship period. Finally, implications for career interventions and for future investigation are offered in light of the results. (Contains 4 tables.)