In line with user involvement and empowerment in individuals who suffer from a severe mental illness, the sense of mastery is important. Few studies have investigated factors that contribute to mastery in individuals with schizophrenia. The aims of the present 18-month follow-up study were to investigate associations between mastery and clinical and sociodemographic factors, needs for care and support and social network, and to investigate whether changes in mastery were related to changes with regard to these aspects in a group of patients (n = 120) with schizophrenia living in the community. Structural interviews were performed at baseline and after 18 months. Pearlin's mastery scale, the Camberwell Assessment of Needs (CAN), the Interview Schedule for Social Interaction (ISSI), and the Brief Psychiatric Rating Scale (BPRS) were used on both interview occasions. A stepwise regression analysis showed a negative relationship between psychopathology, especially affective and negative symptoms, and mastery. Stronger mastery was associated with younger age and less severe basic needs. In total psychopathology, age and basic needs explained 50.7% of the variance in mastery. Changes in mastery were positively correlated to changes in access to social contact but negatively correlated to changes in affective symptoms. In order to target mastery in individuals with schizophrenia, the community-based nursing services need to develop, implement, and evaluate interventions that are effective for psychiatric symptoms, social skills performance, and needs for care and support in areas of living, nutrition, and daytime activities.