Original title: Patient och medaktör. Studier av patientdelaktighet och hur sådan stimuleras och hindras. Title in English: Patient and Co-actor. Studies of patient participation and how this is stimulated and hindered. Language: Swedish with summary in English. Keywords: behaviour, Co-actor, Critical Incident Technique, barriers, focus group, Grounded Theory, nurse-patient relationships, nursing, patient participation. ISBN: 978-91-628-7410-0 The overall aim of this thesis was to contribute to the development of knowledge of what could strengthen patients’ participation in their own care by clarifying the phenomenon patient participation and describe how it is stimulated or hindered, respectively. Data collection were obtained from focus groups (13); with patients (26) and with nurses (31) and interviews; with patients (17) within inpatient somatic care at five hospitals in West Sweden. This thesis includes four papers. Grounded Theory has been described and used to explore the meaning of patient participation in nursing care from a patient point of view. “Insight through consideration” was generated from four interrelated categories: Obliging atmosphere, Emotional response, Concordance and Rights. Grounded Theory has also been used to clarify Registered Nurses’ understanding of patient participation in nursing care. Four properties emerged: Interpersonal procedure, Therapeutic approach, Focus on resources and Opportunities for influence. A thematic content analysis has been described and used to explore barriers for patient participation in nursing care with a special focus on adult patients identified as: Facing own inability, Meeting ignorance, Meeting a paternalistic attitude and Sensing structural barriers. A qualitative approach, using the Critical Incident Technique has been described and used to identify incidents and nurses’ behaviours that influence patients’ participation in nursing care based on patients’ experiences from inpatient somatic care, identified as: Regarded as a person, Engaged through information, Acknowledged as competent, Abandoned without backup, Belittled verbally, Ignored without influence. This thesis has clarified the fact that patient participation is something that needs to be worked on and further developed in health and medical care. This requires nurses as well as leaders at all levels to become aware of the rights and expectations patients have. To achieve optimum patient participation, patients need to be encouraged and supported by knowledgeable and dedicated nurses in order to increase their own control. In order to improve patient participation, traditional structures as well as attitudes of the caregivers need to be questioned and replaced.