The present work reconciles both theoretical and practical aspects relating to the field of collective procedures in general and the preventive phase of the Law of companies in difficulty in particular. This bipolar character is exposed in the most limpid way in order to make the reading as digestible as possible and accessible as well to the learners as to the professionals of the Law, even of the fields close to the present study. As Professor Yves GUYON said so well, "One could believe, and perhaps rightly so, that the questions of the difficulties of companies are the prerogative of economists and company managers, particularly specialists in company diagnosis, but this would be wrong, because all these professions can only justify or qualify a misappropriation if a standardisation is established".