Severe mental illness (SMI) affects patients who, in addition to a mental illness, also have a long treatment history and serious problems with functioning in society. Approximately fifty-five to sixty percent of this patient population are diagnosed with schizophrenia. Schizophrenia and other psychotic disorders account for a huge global burden of disease. History has shown that the way we treat patients with SMI changed over time. One major change has been the extramuralisation of care. In 2005, the directors of the main mental health care institutes in Amsterdam, concluded that very little was known about this group of patients and how they had fared after deinstitutionalisation. This prospective longitudinal study was conducted between 2005 and 2011 in a survey sample of SMI patients treated by the mental health care institutions in Amsterdam. It was decided to focus on four crucial domains: Housing and residential-care patterns, crisis events, victimisation, mortality, and social participation and support. Main findings Part I Residential and care patterns in SMI patients, and profiles associated with a history of multiple crises We found that almost 80% of the patients had an average of almost six changes of address in six years. We also found that just 5% of patients moved from sheltered housing to independent housing during the study period. In Chapter 3, we found that, over a study period of nine years, 15% of the SMI patients had three or more public mental health crisis interventions. On the basis of qualitative research, we identified three profiles for SMI patients. Part II: Victimisation in patients with a severe mental illness, depression, and substance use disorders In Chapter 4 we showed that patients with SMI had a higher risk of being subjected to violence. Inpatients reported the highest rates of crime affecting them. In Chapter 5, we concluded that all outpatients with a depressive disorder, a substance use disorder (SUD) or SMI have a higher risk of falling victim to a crime than the general population. Depressed outpatients and SUD patients were more likely to be affected than SMI outpatients. Part III: Mortality in patients with a severe mental illness We showed that SMI patients have an increased risk of premature mortality. We found a standardised mortality ratio after six years follow-up that was four to five times higher than in the general population in the Netherlands. Almost 11% of our study sample died in the study period, in particular from cardiovascular disease. Part IV: Social participation and the social networks of patients with a severe mental illness We demonstrated that social participation and the inclusion rates of SMI patients were very low: 12% of the patients had a paid job and one fifth of the SMI patients reported that they had had no social contacts over the past month. In Chapter 8, we described that SMI patients were less satisfied than a control group with their overall relationships, that they had fewer friends, and that the social network size was lower. Part V Conclusions This thesis indicates that clinicians, guideline developers, and politicians should be aware that SMI patients are marginalised and victimised, and that there is an urgent need for interventions and financial support to alleviate their situation. We also advise that interventions aimed at improving somatic health care for SMI patients, and access to that care, need to be encouraged and financially supported. We have shown that the ‘revolving door phenomenon’ is still an issue in the treatment of some SMI patients. More and better outpatient facilities for SMI patients should be financially supported and cooperation between chain partners needs to be improved.