Training in the workplace is a key part of VET studies because allows students to develop their skills in a work setting, and gives important information about how well VET studies prepare skilled workers. However, there is little information about factors that influence the efficacy of training in the workplace. Our aim is to evaluate the efficacy of training in the workplace, through the factors that influence training efficacy. We applied a questionnaire of 57 items (5-point Likert scale), a sample of 1,026 VET students in the area of Barcelona, Spain. The results show that the factor “integration into the workplace” is rated more positively by the VET students (4.19), and the factors “social attitudes” and “individual attitudes” get a low score (3.30 and 2.93, respectively). The study allows the introduction of improvements and changes in these practices in order to improve the quality of VET.