The Paper presents the results of research aiming to identify the barriers that hinder effective knowledge sharing (KS) among the participants of business retraining and upgrading programs (FBE - Further Business Education) and to devise methods of overcoming such barriers. Knowledge sharing is understood as a process, in which FBE learners create new knowledge in collaboration with each other by exchanging their explicit and implicit knowledge. Participants in such programs have a number of distinctive features, which determine the special quality of the KS processes within this type of community of practice (CoP). Quite often, they are the leading specialists in particular management issues and have unique knowledge and experience. As highly professional individuals, they detect and respond to the most acute problems arising in business activities, which is a powerful incentive for them to keep learning. The empirical base of the research is formed by the survey of participants in FBE programs at Lomonosov Moscow State University and interviews with directors of the leading Russian business schools, conducted in 2017-2018. The research has shown that the existing potential of collaborative generating of new knowledge through active exchange of explicit and implicit knowledge is far from being fully realized although favourable conditions for effective KS are created. The Paper analyses the main KS hindering barriers, which may rise owing to teachers' insufficient skills in managing expert group discussions and teacher-centered habits, as well as learners' lack of openness or reciprocity, their competing priority and other factors. Overcoming such barriers is facilitated by the introduction of team qualification projects instead of individual graduation work and by the increase in the share of educational interactions aimed at small groups of learners, rather than individual participants. This, however, gives rise to new problems, among which is the contradiction between the group format of the studying process and individual approach to knowledge assessment that dominates the system of control. It is suggested that KS can be promoted by the development of tools that will help synchronize the knowledge exchange processes in the corporate and educational contexts.