Recent research has suggested that mindfulness-based interventions (MBI) for psychosis may be effective in reducing the negative symptoms of schizophrenia (e.g., social withdrawal, lack of motivation) and the distress associated with psychotic symptoms (e.g., hearing voices) and could lead to improvements in functioning and quality of life. MBI research to date has primarily focused on studies of patients with chronic psychotic illness, yet relatively little is known about the use of MBIs for youth recovering from their first episode of psychosis. Results from recently published pilot studies appear promising in terms of the feasibility, acceptability, and potential clinical utility (e.g., improved psychological symptoms) of MBIs for the early psychosis population (Ashcroft et al., 2012; van der Valk et al., 2013; Khoury et al., 2015). The current project team has completed a pilot study at the Prevention and Early Intervention Program for Psychoses (PEPP) at London Health Sciences Centre (LHSC), wherein the "Mindfulness Ambassador Council" (MAC), a 12-week facilitated group intervention promoting mindfulness skills and the development of emotional and social competencies, was shown to be an effective, feasible, and acceptable means of treating youth in the early stages of psychotic illnesses. In follow up to the initial pilot study, the purpose of this study is to perform a multi-site Randomized Control Trial to determine the effectiveness of the MAC group intervention on reducing psychotic disorder symptomatology for transitional aged youth experiencing early psychosis. The main hypothesis, based on previous findings on the use of MBIs in psychotic disorders, including results from our initial pilot study at PEPP, is that youth with early psychosis who participate in the MAC group intervention will experience a reduction in their negative and positive symptoms of psychosis and affective symptoms compared to those receiving treatment as usual (TAU). Furthermore, we expect that youth experiencing early psychosis who participate in MAC will have an improvement in their quality of life, measures of recovery (self-esteem, perceived recovery), perceived coping, assertiveness, mindfulness and cognitive skills, and a reduction in healthcare service utilization (e.g., emergency room visits, inpatient admissions/length of hospitalization).