Psychosocial rehabilitation for people with chronic-severe mental illness mainly aims to social integration by restoring independent functioning in the community, improving quality of life, and addressing risk factors that lead to social disability. Support groups (SG) are usually part of this multilevel mental health process. Given that non-adherence to treatment is a common phenomenon in people with chronic- severe mental illness, the aim of the current study was to identify which factors influence members' attendance in a support group in a vocational training Program of the Psychosocial Rehabilitation Unit of Byron-Kaissariani Community Mental Health Centre. The SG sessions were weekly, with 45-minute duration, opened to any new member of the Program and coordinated by two therapists. Members' demographic and psychiatric data were gathered from the medical records of the Center. Information about SG was obtained from the reports of the sessions. The sample consisted of 18 women, with mean age 38.56 (±6.92) years. Most of them were high school graduates (61.1%), unmarried (83.3%), with low socioeconomic status (55.5%), suffering from a schizophrenic spectrum disorder (61.1%) with a mean duration 15.22 (±8.44) years. Out of 83 sessions in total, twenty-two (26.5%) were in absence of a co-therapist, 11 (13.3%) after a member's entrance or withdrawal and 11 (13.3%) after a session cancellation. Furthermore, an average of four issues was discussed per session, with mental illness (62.7%) and interpersonal relationships (73.5%) being the most popular topics during the sessions. The statistical analysis demonstrated that members' demographic (age, education, marital status, residence, socioeconomic status, working experience) and psychiatric characteristics (diagnosis, illness duration, rehabilitation program experience) were not associated with the attendance rate in the SG. Similarly, the proportion of participants attending the sessions did not seem to be significantly related to the absence of a co-therapist, to a member's entrance or withdrawal and to a session cancellation. In contrast, attendance seemed to be significantly reduced when the topic of a session focused on members' future expectations/goals (having a family, further education, finding a job) (Beta=-0.32, p=0.006). This finding highlights the need for future research in order to incorporate interventions that promote and address future goals and expectations of people with chronic-severe mental illness in psychosocial rehabilitation services.