Ambulance care focuses foremost on medical care and treatment. On the one hand the ambulance service encounters persons suffering acute and severe physical illness or injuries; conversely ambulance patients are described, as being vulnerable to more than just their illness or injury. Ambulance care is provided in an insecure environment and ambulance clinicians have to be prepared for the unexpected. The overall aim of this thesis was to gain understandings of relationships and knowledge in caring, within the ambulance service.Four studies have formed the foundation of this thesis. Three different methods were used; phenomenological hermeneutics (I-II) with individual interviews, qualitative content analysis (III) with focus group conversations and finally a Delphi method (IV). Study I aimed to elucidate the meaning of the relationship with ambulance clinicians as experienced by patients. This was to surrender in dependence of another, being secure in the hands of the ambulance clinician. The situation developed from being lonely before the arrival of the ambulance, to being cared for by the ambulance clinicians and finally being lonely again when transferred to the Emergency Department. Study II aimed to elucidate the meaning of the relationship with the ambulance clinician as experienced by significant others. This was to be lonely together and secure while sharing their lonely struggle for the affected person with the ambulance clinician. At the same time the ambulance clinician’s focus was on the affected person leaving the significant others deserted and lonely. Study III aimed to elucidate ambulance clinicians’ experiences of relationships with patients and significant others. This was encapsulated in the main category; ‘To be personal in a professional role’. Being both personal and professional were found to be intertwined aspects of the relationship. The ambulance clinicians focus on the patient and are involved in creating comfort, having a professional mission to handle their own and the patient’s safety as a priority of the care. Study IV aimed to identify and estimate desired knowledge among Swedish ambulance clinicians from the perspective of ambulance care managers. This embraced a wide spectrum, including both medical and caring knowledge. The highest ranked desirable knowledge areas were; ‘Knowledge to assess the patient’s situation from a holistic perspective’, ‘Medical knowledge to assess and care for different diseases’ and ‘Knowledge to able to care for critically ill patients’. In conclusion, the thesis unfolds a complex understanding of caring in the ambulance service, being secure in insecurity. The patients and significant others are secure in the ambulance clinicians’ presence, but insecure when lonely and powerless. Caring in the ambulance service focuses on the physical disorder, but is understood from the body’s inseparable connection to the lifeworld. Care is fixed in time and often short. The ambulance clinicians have to care for patients and significant others while simultaneously handling an insecure environment. This calls for ambulance clinicians to adopt a holistic approach to care for both patients and significant others, and to acknowledge the whole person.