Swiss vocational education and training (VET) is defined as a dual-track system where apprentices weekly alternate between vocational school and a (real) workplace. At the workplace, they have to keep a learning documentation throughout their training, in which they are expected to regularly document their professional development. The actual use of this documentation remains limited, however, and its potential for learning is clearly underexploited. The study presented in this paper sheds light on the current practices and issues related to the use of such a learning documentation in the Swiss VET system. Semi-structured interviews (N = 29) were conducted with representatives of all the main actors of the Swiss VET system for various professional domains (Industrial & Handicraft, Commerce, and Health & Social Care). The study shows that although they all tend to see the potential of the learning documentation, the different actors of VET do not share a same conception of the aims and functions, both within and across professions. Based on their answers, possible improvements for this tool are discussed, and suggestions are made to enhance its use as a boundary object throughout the training.