The authors describe the barriers related to socio-professional integration of people with severe mental disorders according to different perspectives of various people involved. Focus groups (22) have been conducted in almost every region in Quebec involving 87 participants in vocational rehabilitation programs, 47 non participants and 51 employers. Eighty (80) vocational program administrator completed a questionaire. The barriers identified by these groups are compared with those described in other studies. It seems that the results are similar: the main obstacle is prejudice towards mental illness and people with mental disorders, no matter who is questionned. Barriers to socio-professional integration are reviewed according to the theories of feeling of self-efficiency (Bandura, 1977,1997), causal attribution (Weiner, 1986) and planned behavior (Ajzen, 1991, 1996). Analysis of barriers to socio-professional integration carried out in the light of these three theories, allows to suggest points of reference for new tools and integration strategies.